Sunday, July 30, 2017

#101 - Saturday, July 29, 2017 - Astronomy Double-Header

I may come to regret it on Monday, but I did another all-nighter on Saturday night!  I decided to go for a few galaxies this time.  There aren't many galaxies that are large enough to image well on the 5-inch refractor, but M33 and M101 fit the bill.  And it's a happy coincidence to image M101 on my 101st observing trip.

This trip was actually a double-header - I went first to a park and did an astronomy outreach event there with a few other club members.  It looks like there were about 50 or so people who came, a pretty decent turnout.  We looked at the moon, Jupiter, and Saturn mostly, but I also turned my telescope to M31 Andromeda Galaxy, globular cluster M13, M57 Ring Nebula, M27 Dumbbell Nebula, double star Mizar and Alcor, the Wild Duck Cluster, and the Butterfly Cluster for a few intrepid newly-minted observers.  The two open clusters looked particularly gorgeous this evening, as did M27 and M13.  M31 is difficult to view in my 8-inch Schmidt-Cassegrain, even with a 0.63x focal reducer, and especially because of its low altitude at the time.  It wasn't much more than a fuzzy splotch.  Astronomers might like chasing fuzzy splotches, but the public don't tend to find that as exciting, so I picked out some prettier targets.  Even though the moon was out and we weren't far from the city, there were quite a few stars gracing our presence.
Admiring the first quarter moon before sunset.

I stuck around until about 11 PM, and then packed up and drove over to the observatory.  I had left everything attached to the memorial scope, so I just needed to open up the dome, turn the power back on, sync on a star, and start imaging.  I decided to start with M101, since other targets I had in mind for the evening weren't rising until later.  I got 14 images on it before it got too low.
Date: 29 July 2017
Object: M101 Pinwheel Galaxy
Camera: Nikon D5300
Telescope: Vixen NA140ssf
Accessories: Astronomik CLS filter
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5
Subframes: 14x420s (1h38m), ISO-1600
Darks: 10 (58F)
Biases: 23
Flats: 20
Temperature: 55-57F

I had some difficulty stacking this one - the noise was like crazy again.  I ended up turning off the background calibration, and I tried auto-adaptive weighted average, kappa sigma clipping, and median kappa sigma clipping, but none really improved the noise that much.  I also tried stacking without the flats.  Ultimately having the background calibration turned off was the most helpful, but I had to keep the image pretty dim in order to keep the noise from becoming too ridiculous.  

Around 2 AM, I switched targets to M33.  I'd thought about getting more data on the Helix Nebula, but it wasn't quite as high as I'd like it quite yet, and I didn't have an image of M33 that I was particularly happy with.  This one was noisy too, but not as bad as M101, and I managed to get a decent-looking result (even if it's not quite white-balanced).
Date: 29 July 2017
Object: M33 Triangulum Galaxy
Camera: Nikon D5300
Telescope: Vixen NA140ssf
Accessories: Astronomik CLS filter
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5
Subframes: 12x420s (1h24m), ISO-1600
(3: 13x420s (1h31m))
Darks: 10 (58F)
Biases: 23
Flats: 20
Temperature: 55F

I got a decent amount of the HII regions (the red blotches) as well, woot!  When I was doing some research for including details in my Facebook post, I found out that M33 is actually only 2.4-3 million lightyears away - I knew it was part of the Local Group, but I didn't realize just how close it was.  Neat!

I would have gotten more subframes on M33, but I was tired, and being alone at the observatory all night was starting to get to me.  So I closed up the dome at 3:30 AM and passed out in my sleeping bag on the futon in the warm room again.  In the morning, my haste to get home and avoid all of the bees that were buzzing around and eat some food, in conjunction with my sleep-deprived brain, meant that I accidentally forgot a bunch of stuff there, and had to go back twice!  I was almost out of the park the first time when I remembered that I left my camera bag and tablet in the mini-dome, so I turned around and had to unlock all the locks I'd just locked to get to it.  And then, I was halfway down the drive when I remembered I'd left my accessory bag inside the observatory building, so I had to turn around again and unlock all the locks and contend with the bees.  A gentleman who was walking his dog on the lane was probably very confused.  I'm going to bed early tonight!


Saturday, July 29, 2017

#100 - Friday, July 28, 2017 - 100th Trip!!

This trip out with a telescope marks my 100th since starting two years ago!  It's so awesome that I've been able to get out as often as I have.  Some of those trips were visual observing, some were outreach, some were cloudy, and some were great all-nighters with lots of astrophotography.  It's been an incredible experience so far!


The memorial scope in its dome
Nikon D3100, 18mm @ f/3.5, 13s, ISO-3200

I got out to the observatory at sunset and got the memorial dome opened up and set up.  It would be a while yet until it was dark enough to image, so I set up the D5300 to do some timelapse of the moon and Jupiter setting.  Around 10 PM, I swapped the D5300 for the D3100 plugged into my old tablet (it doesn't work with an intervalometer, nor does it have an internal interval timer unfortunately) and got the D5300 plugged into the Vixen refractor.  It wasn't long after that that I started acquiring images on my first target: the Crescent Nebula.  I just imaged it on my C11, and it appears much smaller in the 5-inch refractor, but because it appears smaller, the light is more concentrated onto fewer pixels, and you can see much more of the inside area.

Date: 28 July 2017
Object: NGC 6888 Crescent Nebula
Camera: Nikon D5300
Telescope: Vixen NA140ssf
Accessories: Astronomik CLS filter
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5
Subframes: 20x420s (2h20m), ISO-1600
Darks: 54
Biases: 16 
Flats: 20
Temperature: 58-65F

I'm pretty stoked that not only can you see much more of the inside detail than I could before, but also a good bit of the background nebulosity!  So awesome!

After that, I switched targets to the Cocoon Nebula, which I've also imaged before on my 11-inch, but it would seem that that entire folder has mysteriously disappeared from my hard drive.  And since my backup drives synchronize, it's not on them either.  Time to start burning Blu-Rays instead...
Date: 28 July 2017
Object: IC 5146 Cocoon Nebula
Camera: Nikon D5300
Telescope: Vixen NA140ssf
Accessories: Astronomik CLS filter
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5
Subframes: 11x420s (1h17m), ISO-1600
Darks: 54
Biases: 16 
Flats: 20
Temperature: 58-65F

This is an emission nebula - hydrogen gas glows red from its hydrogen-alpha transition.  It also includes a dark nebula, molecular dust clouds that obscure background light.  You can see the veins in the nebula itself, as well as the dimming of the background stars surrounding it.

I was going to image the Cocoon for a little longer, but it was approaching zenith and was about to be cut off by the top of the dome, so I changed targets again over to the Helix Nebula.  Since it is much closer to the horizon, there was a lot more background light to remove.
Date: 28 July 2017
Object: NGC 7293 Helix Nebula
Camera: Nikon D5300
Telescope: Vixen NA140ssf
Accessories: Astronomik CLS filter
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5
Subframes: 14x420s (1h38m), ISO-1600
Darks: 54
Biases: 16 
Flats: 20
Temperature: 58-65F

The Helix Nebula is a planetary nebula about 700 lightyears away.  Normally these appear quite small in the telescope, but since this one is so close, it covers nearly the size of the full moon.  The star in the center is the white dwarf that the gas originated from, and the nebula spans 2.5 lightyears now.  

Again, I was going to image this one longer, but I was having a hard time staying awake, and I didn't want to have to get up to move the dome every half hour or so, and then park the scope later.  I watched Netflix all night on my phone in the warm room, which was fun (I finally have unlimited data!)  I unfolded the futon in the warm room, laid out my sleeping bag, and conked out shortly after 4 AM.  Normally I would have set up the tent I brought, but being out at the observatory alone at night is somewhat creepy, so I decided to sleep in the warm room instead.  I slept in only until 9:30 AM, since I wanted to get home and process my images!

A very successful 100th trip!

Here's a timelapse of the evening:



Wednesday, July 26, 2017

#99 - Tuesday, July 25, 2017 - I'm gonna need more coffee

It's a weeknight, Miqaela has "the bug," and of course I can never resist a clear night!  So I picked her up and we got out to the observatory at about 9:30 PM.  I decided to give piggyback imaging a try at the observatory - I figured the light pollution would be too much for short focal lengths, but I thought I'd try at least.  I mounted my D5300 atop the Vixen scope in the memorial dome, and attached a 70-300mm lens to it (also given to me by a club member last year).  At first, I couldn't see Deneb in the live view so I could focus (I had the focal length at ~200mm to try and capture the whole Veil Nebula), but the camera was up too high and was too far forward on the scope for me to use the viewfinder, so I ran inside and grabbed a step stool.  I saw where it was in the viewfinder, and then at last I was able to find it in the live view on my computer as a tiny dim spec.  I focused as best as I could, and then moved over the short distance to the Veil Nebula and took some 3-minute subframes.  They were pretty bright with light pollution, and I couldn't see the nebula at all.  So I scrapped that plan and plugged the D5300 into the Vixen and got guiding set up quickly.

Meanwhile, Miqaela got her scope set up and guiding pretty much without my help.  Woot! She borrowed my Orion ST-80 again.  However, her camera wasn't completely fastened into the eyepiece tube, so it slid out of focus a few times, and re-focusing at such a short focal length is difficult, since the stars always appear small and dim.  Between this and my attempts to piggyback, neither one of us started acquiring images until well after 11 PM.  Since it was a week night, my plan was to have us pack up around 12:30 AM, so that didn't leave us much time.

I managed to grab 14x7-minute subframes on the Western Veil Nebula, which I haven't imaged before.  The subs looked very promising, but the first iteration out of DeepSkyStacker came out very noisy, so I ditched the flats and tried again (I don't have an exact position marked on the scope, since I don't own it, so I just align the accessory shoe with the piggyback mount on top of the telescope tube, but it is inexact).  Maybe I can mark it with tape or something removable.  The stack without flats came out a little cleaner, but not much.  Trying out different debayering settings and stacking settings was still giving me very noisy images, although using "Auto Adaptive Weighted Average" in the "Lights" tab of the stacking parameters window seemed to do better, and I added the flats back in.
Date: 25 July 2017
Location: John Bryan State Park Observatory
Object: NGC 6960 Western Veil Nebula
Camera: Nikon D5300
Telescope: Vixen na140ssf
Accessories: Astronomik CLS filter
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5
Subframes: 13x420s (1h31m), ISO-1600
Darks: 10
Biases: 20
Flats: 20
Temperature: 58-60F 
See on AstroBin

Also, guiding was so good on the memorial scope that I may need to start dithering!  Dithering is where you can have PHD or your image capture program (through PHD) move the telescope a pixel or two every so many frames so that you don't end up with one of the camera's hot pixels on the same spot in every frame.  Usually periodic tracking error pretty much takes care of this for me (even when I guide it shows up still, just more slowly), but guiding was so tight that my images barely moved, if they moved at all!

While my images were going, I also ran around with my D3100 and nabbed some Milky Way images, as well as the  Big Dipper.  One of the Green Bank attendees pointed out the "Green Bank Telescope" asterism in Ursa Major, and I was hoping to make a picture to show that.  I'm still figuring out how to make constellation stars stand out, so I'll post it here when I finish it.

We did indeed pack up at 12:30 AM and I got to bed by 2:15 AM.  Thank goodness for cheap office coffee to help me get through the afternoon!

Miqaela's image came out lacking the red, but that's to be expected from an achromatic refractor, it looks like.  We didn't quite get the field-of-view moved up high enough to see the Pickering region in between the Eastern and Western Veil Nebulae, but you can kind of see some of it in the lower parts of both my and her images.  Still pretty neat what you can capture with a cheap refractor!  And she got some pretty neat star colors.
Western Veil Nebula, Nikon D5300, Orion ST-80
4x300s, ISO-1600

There was also a very nice ISS pass - almost straight overhead!  As well as an Iridium flare.  I misjudged where the flare was going to occur, so I only caught it in the side of the frame (and out of focus).
International Space Station, Nikon D3100, 18mm @ f/3.5, 30s, ISO-800

Iridium flare (on the right edge of the frame), Nikon D3100, 18mm @ f/3.5, 30s, ISO,400
(Now I know what some of those UFO pictures are.)

A short but productive evening!


Monday, July 24, 2017

#98 - Saturday, July 22, 2017 - Green Bank Star Quest Night 4

I put in a bunch of raffle tickets for a Canon T5i, but didn't win.  Darn!  Astrophotographer Brent Maynard gave several talks on astrophotography, and talked about the Magic Lantern tool for Canons, which lets you access a great deal of the camera's settings, and he was offering to modify it for the winner.  That would have been awesome!

It was cloudy again that night, but this time it was due to a bit thunderstorm rolling through.  After the raffle, Miqaela and I drove down to the observing field to batten down the hatches on our gear, which we didn't end up having a chance to put away earlier that day, and I grabbed my camera and tripod while I was down there.  The lightning was awesome, but I missed the bulk of it by the time we got back up to the bunkhouse, where I set up my camera to try and capture some lightning images.  There was a massive strike nearby that shook the bunkhouse!  Out of some 1,300 frames I took facing different directions as the storm moved, I managed to get only two with lightning, and only one in raw format.  I touched up both of them anyway - check it out!
Lightning at the Green Bank Observatory
18mm @ f/3.5, 1s, ISO-200

Lightning at the Green Bank Observatory
18mm @ f/3.5, 2s, ISO-200

The orange glow around the light on the lower left is from a water droplet on the lens.

I wish I'd grabbed my camera sooner, I could have gotten some lightning shots with the Green Bank Telescope in the background!

Needless to say, no observing was done that night.  Our gear survived the storm, and we packed up Sunday morning and headed home.  We had a great time!  Lots of awesome talks, met a lot of new people, and saw a few friends we'd met previously at other star parties and events.

Here's a timelapse I made over the course of the weekend - I didn't get as much as I'd hoped to get, but still kind of cool!


And, also, a timelapse of us tearing our equipment down also came out super cool.



#97 - Friday, July 21, 2017 - Green Bank Star Quest Night 3

Well, our luck couldn't hold out for much longer - we had a cloudy night.  Well, it wasn't even entirely cloudy, it was sometimes clear up high, but not enough for us to get the telescopes aligned and ready to go.  I knew that if we started, it would cloud up by the time we were finished, of course!  I tried to take some timelapse, but ground-level fog rolled in.  We stayed up for a while processing our images, but went to bed at about 1:30 AM.


Sunday, July 23, 2017

#96 - Thursday, July 20, 2017 - Green Bank Star Quest Night 2

We got lucky again - another clear night!  I was looking iffy, but it started clearing up, and we quickly got our telescopes re-aligned.  Earlier that day, I'd replaced Miqaela's Newtonian with my Orion ST-80, a 400mm focal length refractor that I have usually used for guiding, and once used for imaging (see my Orion Nebula #9 image).  I had also fixed the finderscope earlier, so aligning went pretty quickly, and then we swapped out the finderscope for the 50mm mini-guider.  Before long, she was getting promising 6-minute-long subframes on the North American Nebula.  I had encouraged her to go for an easier target first, like the Andromeda Galaxy, but there were clouds just beneath Cassiopeia (and really all around the sky below about 35 degrees altitude), so Cygnus was the most promising area for clear skies.  We processed her image over the next two days, and it came out great!
Date: 20 July 2017
Location: Green Bank Radio Observatory, WV
Object: NGC 7000 North American Nebula
Camera: Nikon D5300
Telescope: Orion ST-80
Accessories: N/A
Mount: Celestron Advanced VX
Guide scope: Orion 50mm Mini-Guide Scope
Guide camera: ZWO ASI 120MM
Subframes: 24x360s, ISO-1600
Darks: 9
Biases: 20
Flats: 20

I also did a configuration change - I moved my camera up to the Borg and put on my own Orion 50mm guider, since there are some summertime nebulae up in Cygnus I need a larger FOV for.  While Miqaela was imaging the North America nebula, I was right next door in the Pelican Nebula, taking 10-minute (!!) subframes.  I figured I'd snag some darks the next night when it was going to be cloudy.  What was really amazing about being out where it was so dark was that I was shooting 10-minute-long frames on an f/6.6, 76mm refractor with no light pollution filter, and my entire histogram was still in the first quadrant.  It was amazing.
I didn't have the mini-guidescope on at the time, but otherwise, here is my Borg imaging setup from the second night.  My cables were also put away - it's usually a bit messier.

This time, I also swapped power sources - I put the scope on the 7 Ah battery, and the dew heaters on the 17.  That worked great - the 7 Ah ran my telescope all night (although it was flashing yellow when we were packing up), and the 17 Ah still had power left in it at the end of the night.  Oh, also, I finally did get a field flattener for the Borg - someone on Cloudy Nights recommended one by Hotech, which is a non-reducing, self-centering field flattener for any refractor with a focal ratio f/5-f/8, and it's half the cost of the one Borg was selling.  Until I took a set of flats, it stacked really weird in DeepSkyStacker though - like, the bottom of the image was warped, and the red and green channels separated in that region, like someone was pushing their hand up under a blanket made of this picture.  I didn't save one with this effect, but I should have, because it was crazy.  But adding flats fixed the problem.  (For the record, you can't see it in the subframes, so I have no idea what that is all about).

Date: 20 July 2017
Location: Green Bank Radio Observatory, WV
Object: IC 5070 Pelican Nebula
Camera: Nikon D5300
Telescope: Borg 76ED piggybacked on C11
Accessories: Hotech SCA field flattener
Mount: Celestron CGE Pro
Guide scope: Orion 50mm
Guide camera: QHY5
Subframes: 17x600s (2h50m), ISO-1600
Darks: 10
Biases: 18 
Flats: 20
Temperature: 59-65 F 
See on AstroBin

I don't see a pelican, but I do see some pretty colors!  Hydrogen alpha (the red light) is hard to get with an unmodified DSLR, and after meeting a guy at the star party who modifies Canons, I've started thinking about doing it again.  (Well, paying someone else to do it - I'm handy, but I'd probably break it, since it would be my first attempt at it).  Modifying it would allow much more of the red light through the camera's color-balancing filter.  

After two and a half hours on the North America Nebula, the sky had cleared up some more, so Miqaela finally got to image the photogenic Andromeda Galaxy, and she got a great image!
Date: 20 July 2017
Location: Green Bank Radio Observatory, WV
Object: M31 Andromeda Galaxy
Camera: Nikon D5300
Telescope: Orion ST-80
Accessories: N/A
Mount: Celestron Advanced VX
Guide scope: Orion 50mm Mini-Guide Scope
Guide camera: ZWO ASI 120MM
Subframes: 21x300s, ISO-1600
Darks: 9
Biases: 20
Flats: 20

One drawback of shooting through the Orion ST-80 is that it's an achromatic doublet, meaning that there is chromatic aberration.  Since it's more meant to be a terrestrial viewing or guide scope, this isn't usually a problem, but for deep sky imaging, you'll start to notice.  It also has some coma.  In the case of the Andromeda image, the central stars turned out more red and the outer ones more green.  We may be able to process that out, but I don't quite know how yet.  Despite that, however, I think her images came out great!  Definitely better than my first year's worth of astro images - although it helps to have someone coaching each step, rather than my stumbling through reading forums, books, and getting bits and pieces of a variety of people.  :)  Of course, it can sometimes be the blind leading the blind here, since I haven't been at it for very long myself!

My second target for the night was the Eastern Veil Nebula, something else I've imaged before but it turned out very dim in my Orion ST-80 only taking 1-minute frames last August from my decidedly less dark home location (see that image here).  This one came out WAY awesome, despite the fact that I only got three subframes before some impending clouds with lightning made us decide to go to bed.
Date: 20 July 2017
Location: Green Bank Radio Observatory, WV
Object: Eastern Veil Nebula
Camera: Nikon D5300
Telescope: Borg 76ED piggybacked on C11
Accessories: Hotech SCA field flattener
Mount: Celestron CGE Pro
Guide scope: Orion 50mm
Guide camera: QHY5
Subframes: 3x420s (21m), ISO-1600
Darks: 10 
Biases: 16
Flats: 20
Temperature: 58F (14.4 C)
See on AstroBin

Sometime, I'm going to piggyback my DSLR with like a 200mm focal length lens or something and get the entire Veil Nebula/Cygnus Loop.  That'd be awesome!!  The Veil Nebula is a supernova remnant from a supernova that happened somewhere between 3,000-6,000 BC.  It's about 1,470 lightyears away, and the whole thing is about 100 lightyears across now.  It is bright enough to see in a telescope too - I looked at the Eastern, Western, and even the central portion known as the Pickering triangle through a 12-inch Dob with an OIII filter.  It was incredible!  I was so glad to get to see it at last!  It jumped right out with how dark it was up at zenith.

We went to bed at 4:30 AM again after taking a little more time to secure the tarps over our scopes and make sure all of our other stuff was away in tubs.  It's a good thing we did too, because it rained like crazy that morning and throughout the day!  A little water got into my accessory 3-drawer bin (which mostly contains screwdrivers, cables, and cleaning tools), and into Miqaela's empty mount box, but otherwise everything stayed nice and dry.  

We were basically the only ones at the entire star party who stayed up all night (and definitely the only women), so sleeping late was difficult due to people talking loudly at 7:30 AM, but we managed to get enough sleep to continue to function the rest of the weekend.


#95 - Wednesday, July 19, 2017 - Green Bank Star Quest!! Night 1

My minion Miqaela and I made it to the Green Bank Star Quest!  After checking in and being shown to the bunkhouse (which I will say is waaaaay nicer digs than the Texas Star Party, haha), we drove down to the observing field in the shadow of the Green Bank Telescope, a football-field-sized radio dish of awesome, and got set up.

Because of our proximity to the radio dish, all of our devices had to be in airplane mode, but they did allow us to bring cameras and laptops down to the observing field.  Luckily, I already run everything with cables and don't do any wireless triggering, so that wasn't an issue.  We did have to do some power management planning though, since there is no AC power down on the field, besides a barn where they have a couple of outlets that can be used to re-charge things.  I brought my four Nikon batteries, a 7 amp-hour power tank, and a 17 amp-hour power tank I won last year.  Miqaela brought three Nikon batteries and a 7 Ah power tank.  I can run my tablet off any USB port, such as the ones on the power tank or my external cell phone recharger battery, but Miqaela only had a laptop, so we implemented every power-save setting we could find, and kept the lid closed as much as possible.

We had great luck the first night - it was dazzlingly clear!  WOW the sky was incredible.  Especially at zenith - the stars looked so close!  We even found Andromeda naked-eye later that night.  

Unfortunately, our equipment was less cooperative than the sky.  I was having some USB issues, likely caused by trying to run 5 USB devices on one USB port (my camera, Miqaela's camera, my guide camera, my telescope, and my digital thermometer), as well as some weird "no response" codes on my hand controller, and I didn't measure north close enough when I set up the tripod during the daytime and ended up having to pick up and rotate the telescope (no easy task when it weighs some 170 lbs!)  This was Miqaela's first attempt at guiding, so we were bound to hit some snags.  We had difficulty even getting her mount to align - her finderscope was broken, and I bent the contact in mine while trying to replace the battery, so she had great difficulty aligning her scope.  Even after she managed to do it, it started having bad gotos, and we had to re-start.  After several attempts, I finally just put in a 40mm eyepiece and got down on my knees and sighted up the tube to align, and I was able to get her aligned, at last.  We got her an Orion 50mm mini guide scope for her Celestron 130 SLT Newtonian telescope, which as a 650mm focal length (the Orion 50mm has a 162mm focal length, and is advertised to be able to guide scopes up to 1500mm long).  However, the mirror is not far enough up in the tube for her to be able to focus her DSLR, so she needs to use a 2x Barlow in order to reach focus.  This makes the effective focal length of her scope 1300mm, which on her Celestron Advanced VX mount turned out to be just beyond its capability to guide.  We finally called it a night on hers.

After getting pointed roughly north, I was attempting to polar align, and realized that the CGE Pro wasn't going to quite be able to make it to 38.5 degrees in altitude (for 38.5 degrees N latitude).  It's got this weird configuration where you have to move the plate with the altitude screw down to a lower position in order to reach altitudes 40-65 degrees.  I had it still set for 10-40 degrees from the Texas Star Party, but the screw reached its tightest position at only 38 degrees.  Luckily, a gentleman and meteorite guru I met at my club's annual symposium, Dave Holden, had a great idea - just put a thick nut on the bottom of it!  This gave me the extra height I needed to polar align.  Woo hoo!   Finally, after midnight, I started imaging my target for the evening - the Crescent Nebula.  I've imaged it twice before, and could see the edge but none of the center, but I was hoping from this dark location, I would be able to see more of the inner portion.  The next day, I realized that I had forgotten to attach the focal reducer!  I was wondering why my subframes were so dim - imaging at f/10 is hard.  But it came out all right anyway!  This was also my first time guiding with the Borg refractor, and the extra 100mm of focal length helped - I was able to go at least 7 minutes, and I didn't go longer only because I didn't have any darks to match.  (Guess I'd better start taking some for star parties!)
Date: 19 July 2017
Location: Green Bank Radio Observatory, WV
Object: NGC 6888 Crescent Nebula
Camera: Nikon D5300
Telescope: Celestron C11
Accessories: (no focal reducer, oops!)
Mount: Celestron CGE Pro
Guide scope: Borg 76ED
Guide camera: QHY5
Subframes: 12x420s, ISO-1600
Darks: 12
Biases: 20
Flats: 0
Temperature: 56-58 F (13.5 C)
See on AstroBin

Because I forgot the focal reducer, I also didn't have any flats to match, so I took some the next day.  I took them after I had initially processed it though because I'm impatient, but I ended up actually liking the version with the flats better - the noise wasn't as bad, strangely.  Maybe I need to re-look at how I take my flats.

After an hour and a half, it was time for a meridian flip, but I decided to change targets instead to the Cocoon Nebula.  I took a 5-minute subframe, but couldn't see a single thing - probably because of the lack of focal reducer.  It's mostly a hydrogen alpha nebula, a wavelength that my unmodified DSLR isn't sensitive to at all, so I really need that focal reduction in order to get anything.  I tried the Pinwheel Galaxy too (M33), but it was also super dim.  Then, the 7 Ah battery I was using to power all of my dew heaters (two for my scope and guide scope, one for Miqaela's guide scope, and one for my Nikon D3100 running timelapse) finally died, so I moved my camera up to the Borg, which with its smaller objective and plastic dew shield seems to be more resistant to dew.  I tried for Andromeda, but it was dewing up already too, so then at 4:30 AM I called it a night.  I woke a snoozing Miqaela from the car, we put our tarps over the scopes, and trudged back up the hill to the bunkhouse.  A difficult night, but it was awesome just being under those gorgeous dark skies and watching the Green Bank Telescope move every so often.



Sunday, July 16, 2017

#94 - Saturday, July 16, 2017

The first part of the evening was the Camper Stargaze.  The club hosts these throughout the summer in the parking lot next to the playground, and lots of club members come out and set up gear to show off the night sky to both campers at the park and people who hear about the event through Facebook/word-of-mouth/etc.  Last month’s event apparently had 250-300 people, which is the biggest crowd we’ve yet had!  We think people are getting more interested because of the upcoming solar eclipse.  Last night didn’t have quite that number, but I heard it was over 150.  There were a lot of club members present with their gear, so it didn’t feel like it was that many – I maybe had 20 people total come by.  We looked at Jupiter, M51, and M13.  M51 was difficult to see – I could make out the two cores, but some of the guests had trouble, but M13 was very nice, especially with averted vision.  It was right at zenith, but luckily I had the telescope far enough forward in the mount that the star diagonal didn’t hit the mount like it usually does that high.  Jupiter looked pretty good – I put on the 13mm eyepiece, which I think I need to clean after so many kids’ faces smudging it up.  But the view was still nice, you could see the two main cloud bands and its four Galilean moons.  Callisto was just above the planet, very close to it.  I had several little kids come through, and there’s always one who is very knowledgeable, and it’s fun to watch them show off.  This time it was a young boy, maybe 5 or 6, who could name all of the planets in order.  The family of one of my Girl Scouts came out as well, and I left the event at the time it was set to end, although there were still people there, in order to show them the observatory as part of earning the Sky badge.  It killed me to leave when people were still looking through scopes, but I also had an ulterior motive: I wanted to do some imaging before the moon came up!  We looked at a few more things in the memorial scope: the Lagoon Nebula and the Andromeda Galaxy.  The 26mm 2-inch eyepiece I grabbed was just too much FOV though, so there wasn’t much detail on anything.
            
After doing a tour of the observatory and the dome where I image, my Girl Scout and her family took off, and I got busy getting set up on the memorial scope.  I only had about an hour and a half though until the moon was up, so I scrapped my plans for imaging the Veil Nebula and picked an easier target instead: the Trifid Nebula.  I got about 14 progressively brighter 6-minute frames before I called it quits; my blue histogram peak was about to fall off the right edge.  I lost one of my frames when the mount did the thing again like on 4th of July weekend, where the hand controller acted like I was pressing and holding the menu key, and it looks like it stopped tracking or something for a bit, since PHD showed some huge spikes trying to compensate.  I hit the menu key a few times, and a few other buttons, and then let it sit for a moment, and it stopped and continued tracking where it left off.  Night saved!  I hope this doesn’t keep happening because a replacement hand controller for the Losmandy Gemini is expensive…

            
Anyways, here’s the image!  Light pollution removal algorithms are truly magical, I have decided.  I think I’ll use this one for my Photoshop tutorial.
Date: 15 July 2017
Object: M20 Trifid Nebula (and M21 open cluster)
Camera: Nikon D5300
Telescope: Vixen na140ssf
Accessories: Astronomik CLS filter
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5
Subframes: 13x360s (1h18m)
Darks: 23
Biases: 20
Flats: 20
Temperature: 59-61F (15.5C)

Open cluster M21 is in there too – I was going to center M20, but then decided it’d be nice to have the cluster there as well.  I’m also quite pleased with the lovely shade of pink-red that came out.  I didn’t adjust that color at all besides white-balancing use the black point. 
            
I left the observatory around 2:30 AM, and got to bed about 3:15 AM.  Unless it clears up Monday night, my next log entry will be from the Green Bank Star Quest!



All Caught Up

All right, quick post here - I am all caught up on posting my previous log entries!  Now I can start writing my log entries with this blog in mind, so I'll include more detail and explanation of things.  Starting with last night's outing.

I think so far it's been mostly members of my astronomy club checking this out, and the response has been great so far!  Now just to reach more people!  This has been a fun experiment so far.

I've got a lot more tutorials planned, but if you have suggestions, or questions you'd like answered (either astrophotography related, or scientific!), please comment!

Thanks for reading!

-AstronoMolly/mollycule


Saturday, July 15, 2017

A Super-Duper Primer of Astrophotography Part 8 - Post-Processing with Freeware

Stacking is only part of what makes a great image.  After getting an image out of DeepSkyStacker, there are still further steps to take that will complete the transformation of your noisy, dim, light-polluted subframes into a fantastic work of celestial art.  I'm going to write two separate tutorials - one for using freeware, and one for Photoshop.  Freeware can get you some good results, but Photoshop has some truly amazing algorithms that will blow freeware out of the water (there's a reason it costs money).  But I'll start with the freeware to show that there are still some things you can do before committing to buying a subscription for Photoshop.

"Fake" vs "Real"

It might feel at first like putting an image through an image manipulation program like GIMP or Photoshop makes it somehow less real.  I mean, you can make an image look like whatever you want, right?  While this is true, it is important to remember that what you are really doing with image processing is bringing forth the photons that are really there, but are obscured by noise and light pollution.  

My personal image processing philosophy is to keep the image as close to reality as possible.  Now, knowing what reality looks like can be very difficult.  No one has been on a spaceship and flown close enough to these objects to see what they look like, and every camera is going to capture that light-information a little differently.  Looking at other people's images online can help, but you have to keep in mind that even these images were all processed, and many use narrowband filters that are false-colorized or add color to wavelengths that we normally wouldn't be able to see (IR, UV, x-ray, etc).  Among close color renditions of red-green-blue imagery, there can still be vast differences of opinion - look up some images of M27, the Dumbbell Nebula, for example.  Is it green, or is it blue??  My camera tends to show more of a blue, but sometimes it can look more teal.  So what is truly real?  Basically what I try to do is to keep the expression of colors as my camera captures them, accounting for the knowledge that I will have less-intense red than I should, and if I use a light pollution filter, there will be a blue tinge to everything.  I will white-balance and enhance/suppress colors with that knowledge.  

Some astrophotographers prefer to make their images more artistic.  They will oversaturate colors, blow out reds or blues, change the hues of some colors in order to bring out differences in color, and other things in order to get neat-looking images or to point out interesting scientific phenomena.  I occasionally do this, but I don't post these images as astrophotography - I'll specifically call them my "artistic" take.  But that is up to each person.  When I get to a point when I can start selling my images, I might make more of these "artistic" versions, since they can be prettier and more interesting to look at than the "accurate" versions.  

The way you edit your images is up to you - there's no doctoral defense committee that is going to question your methods or your data.  So have fun, and make of your images what you want!  And always be transparent - don't make your Pleaides Cluster images all red and then tell people that's what it looks like in reality.  (Although a Pleaides triptych in red, green, and blue sounds neat!)

GIMP

GIMP is short for GNU Image Manipulation Program.  GNU is itself a recursive acronym for "GNU's Not Unix," a project to build a Unix-like operating system that is not actually Unix-based (Mac and Linux are both Unix-based, for example).  There are many pieces of software out there that fall under the GNU label.   (Don't worry about the name - GIMP has versions for Windows, Mac, Linux, and GNU).  Because it's open-source, many users have written plug-ins for it to do all kinds of stuff.  Basically, it's a free mimic of Photoshop.

First, go find your favorite version of the TIF you saved out of DeepSkyStacker.  I'll edit my Rosette Nebula image for this tutorial.  Ignore the warning about GIMP only being able to handle 8 bits per channel if you get it.

Now, the following steps don't necessarily need to be done in the order I present them, but this is the order I usually do stuff in.  Go to Colors -> Levels.  This is where you can "stretch" your histogram and set your black point.  Start by moving in from the left - in the histogram for my image, you can see that the main peak is pretty far over to the right, which is why the background is so light.  Move the leftmost arrow close to the main peak, but try not to cut off any of it - you can lose faint details on your object.
I don't really end up stretching my histogram very much, since it usually comes out of DSS pretty well stretched.  I'll just cut off the bottom, which effectively moves the whole thing to the left, making your background blacker.  Click OK.

Re-open Colors -> Levels.  Setting the black point is a quick way to white-balance your image, but can sometimes give you weird results.  Click on the dropper icon (next to the box that says "Auto"), and then click on an area of your image that is empty and dark.  You will see this re-color your image.  If it comes out weird, try a different spot - you may have unknowingly clicked on a noisy pixel, or a tiny star.  You can also try the Auto button, which will set the black, gray, and white points for you.

See?  It's looking better already.

Now go to Colors -> Curves.  This will show a histogram with a diagonal line drawn across it.  Basically, the line represents an input-output value for every intensity from black (left) to white (right).  The horizontal axis is the input value, and the vertical axis is the output value.  For example, if you clicked on the line near the left and dragged it down to the bottom, it would change the input value to a lower output value, lowering the visual intensity of the blacker parts of the image (make the blacks blacker).  If you clicked on the line near the right side of the image and dragged it to the top, it would increase the visual intensity of the whiter parts of the image (making the whites whiter).  Go easy in this section - it's very easy to add noise here, or blow out parts of your image.  Usually here, I grab the middle of the line and bring it up a bit to increase the brightness of the midtones (where your object lives).  I sometimes also drag the lowest, leftmost part of the line to the floor of the plot, darkening the black areas a bit more.  

You can do this for the image as a whole, or you can break it down by color channel - red, green, and blue by clicking on the box next to Channel and choosing one of those color channels.  I will frequently go to the Red channel and bump up the red intensity, since shooting with a DSLR means that you lose quite a bit of red.  

Play with this for a while to get familiar with what moving the line does, and then decide how you want your image to look.  Changing the line will show a preview on the image, but if you click Cancel, it will reset it to before you opened the Curves window.  To make a change and "save" it before making another change, click OK, and then re-open the Curves window (Colors -> Curves) to do your next Curves edit.  I do this so that I don't have to re-do several steps if I change something and then don't like it.


With nebula images, usually I don't need to do much color-balancing after DeepSkyStacker, even if I use a light pollution filter.  So I'm going to open up a galaxy image now and show some additional color-balancing tools.

Here is an image out of DeepSkyStacker that I took recently of M101.  I used a light pollution filter, so it appears quite blue.
When I go search for M101 images online, generally the arms are a bluer share of blue, with red star-forming regions, and a yellow core.

I'll usually let the image processing program take a stab at white-balancing - but sometimes the results are really bad!
This is from clicking the "Auto" button in the Levels window.  When I choose a black point instead, the background gets blacker, but M101 still looks just as blue.  Choosing a star as a white point didn't change anything in this case.  So I'm still stuck with a blue M101.

Once you've done Levels and Curves, go to Colors -> Color Balance.  Here, you can adjust the color balance of CMY (cyan, magenta, yellow) versus RGB (red, green, blue).  Make sure you adjust for all three of the ranges - shadows, midtones, and highlights - until you get something you are happy with.  After messing around with all of the sliders, I got something with whitish-bluish arms, some red star-forming regions, and an almost-yellowish core.

Not too shabby!  Now I would go play around with the Curves tool some more.

You can also adjust the huge and saturation of your colors.  Go to Colors -> Hue-Saturation.  You will see a wheel of Red, Magenta, Blue, Cyan, Green, and Yellow, as well as Master in the middle.  I'll use this tool sometimes to further bump up the redness of my red if I'm imaging something with a ton of red, like the Eagle Nebula or the Rosette Nebula.  Basically what it does is let you change the hue (the color - you can make all of the reds blue instead), the lightness (the shade of the color - for red, burgandy to light pink, for example), and the saturation (how "strongly" the color shows up in the image).  For this image, changing these attributes doesn't drastically change the image (except for changing the hue of cyan), but I did make the cyan a little bluer.  These changes would be more obvious on a nebula image.

Finally, when you are satisfied, click File -> Export As... to save out a TIF (for future re-edits) and a JPG (to post to the internet).  

Now, as you may notice, there are a lot more tools available.  Many of them are filters that add interesting effects to images, and won't do much for your astroimages.  Others include healing tools, clone stampers, etc, which can help get rid of dust in your optical train if your flats are not the exact same orientation as your camera was that night.  I have not explored much beyond the tools I've shown (at least, not in GIMP), but feel free to try out all kinds of stuff on your images!  And there is a wealth of knowledge out there about how to use GIMP.

Noise

Even with darks and biases, you are still going to have noise, particularly with a DSLR, since they tend to not be cooled and are not optimized for low-light imaging.  Not to worry, there are ways of "removing" the noise so that your images look a little better.  An AstroBin user told me about a piece of software called Noiseware, which is not freeware but has a free version that lets you save out JPGs and works pretty well.

If you take a close look at the Rosette Nebula image, you can see a lot of "graininess," which is called that in the film world, but is called noise in the digital world.  While we can't remove it in a strict sense, we can reduce its appearance.  

Open up Noiseware and import your TIF.  It will look extra noisy here.  

You can see that there are a number of settings.  This program can both add noise or suppress it, so set the "Noise Level Adjustment" sliders to 0% if they aren't already.  Under the "Noise Suppression," start with the defaults, and see how that looks.  I would recommend staying away from 100% - basically what noise suppression is doing is smoothing several pixels across each other to reduce the appearance of noise.  But too much smoothing will smooth out the fine details of your image as well, and those fine details are what we really love in astrophotography.  So split the difference.  Click Go when you've set your settings.

Now check out your image - much better!
 Let's zoom in on that.


Miraculous!
Now, the free version will unfortunately only let you save out JPGs, although the (rather expensive) paid version will let you save out TIFFs (and has a batch mode).  On the other hand, Photoshop has a built-in tool as well.

Drumroll...

And now you're done!  Go back and look at your subframes, and then the image out of DeepSkyStacker, and then the image you just created.  Amazing what a little tweaking can do!  And there is so much more out there.  Some people spend hours post-processing their photos.  I tend to spend about 20 minutes after DeepSkyStacker is done stacking working on mine because I just don't know what all to do with it yet.  But there you have it!  So now you can spend all of your money on astronomy gear instead of software. :)