NGC 925 REDO

So I guess I was right about the bad data ruining my NGC 925 shot.  Well, "ruining" may be too strong of a verb.   I re-stacked the frames only taking exposures that were 21 degrees and cooler.   As an experiment, I did a stack without BIAS frames and a stack with BIAS frames, but no dark frames.    Both resulted in a cleaner image with noticeably less noise which meant I could push the image further in terms of pulling out small detail in the galaxy's arms.

While I was getting more exposures in my original stack, I was basically ADDING UNNECESSARY NOISE with all those exposures between 22-29 degrees celsius.   I immediately started researching ways to non-invasively cool the Canon T3i.  About a year ago, I bought some aluminum sheet and a cooler to make one of Gary Honis's DSLR coolers.  But I wonder if I would get the same result by simply attaching the peltier/heatsink/fan combo to the back of the camera using the tripod socket?   Hm...   I'm going to have to figure something out since every time it dips above 45 degrees F my camera has heat stroke.

Anyways, here's the processed shot of NGC 925 using better data:

So get this...  this is 61 x 600 sec light frames, NO DARK FRAMES, 20 flat frames, and 44 bias frames!!!   Brought into Lightroom and Photoshop.  This is about a 70% crop of the original image.

This image is ever-so slightly less noisy than the version with dark frames and no bias frames.

Weird.

Anyways, here's an even tighter crop:

It's cool to pick out all the little galaxies in the background.  I can make out about 25 in this close-up crop.

Trying to Push Forward... M33, IC 405 (Flaming Star Nebula), and NGC 925

I've been trying to ride the momentum of the Van Vleck trip by taking a few shots back home.   I upped the ante by going for multiple nights on 3 targets.   I also switched scopes -- going back to the Tak 102 with the Televue .8x Focal Reducer/Flattener.   One of the things I immediately noticed was that the flattener tends to enlarge the size of the stars in the image.   I noticed this when I did a test shot of M45 (Pleiades) and the stars were gigantic.   But I figured I would just move forward and see what I could I get.

My first target was M33 -- the big galaxy in Triangulum:

This is one of the largest galaxies in the sky -- next to M31 (Andromeda) and the Large and Small Magellanic Clouds.   It's about 2.7 million light years away so the image you're seeing is what it looked like 2.7 million years ago!  All things considered, it's actually right next door compared to most of the small galaxies you can view through a telescope.

The shot is 64 x 5 minute images at 1600 ISO through the Takahashi 102 @ F/6.4 (w/.8x Focal Reducer/Flattener - part #RFL-4087).   I collected the data over three nights - around 360 minutes total.   But I let Deep Sky Stacker take the best 64 frames (5 hours, 20 minutes).  Everything is riding on the AP900 and the QHY 5II-L is guiding through the Orion Miniguider mounted to the scope.

It took me several attempts (maybe 8-9 hours) of processing to get this version which I'm OK with.   I'm happy that the H-a regions (red areas) in the arms came out pretty well.   The brightest H-a region (NGC 604) located in the lower right of the image is obviously blown out.  A more fastidious imager would reshoot about 40 - 1 minute shots.  :/   There are several globular clusters visible -- but they appear as stars.   Also, there are a couple of interesting blue nebulae visible -- most noticeable is IC 132 in the lower middle part of the image.

My approach during the 6 days of imaging was to try to shoot one target for a few hours in the early evening (9:30 to midnight) and then another target for later (1 AM - 4:30 AM).    For M33, this meant about 2-3 hours early in the evening for three nights.   Unfortunately, after the first night, I got hit by an intestinal bug and I had to bow out for 2 nights to recover.  However, the first night I did collect data on M33 and IC 405.

When I finally got out again, the weather turned out to be unstable after midnight for two nights in a row.   So I only ended up collecting 50 five minute frames of IC 405 (Flaming Star Nebula) which is located in Auriga.  Of the 50 frames, I only stacked 42 frames (210 minutes) which is really not enough.

This shot also consisted of 24 darks, 22 flats, and 20 bias frames.  It's also a 75 percent crop of the original image.  The right side of the nebula is noisy and was only barely visible on the single frames that I was collecting.   Everything else equipment wise is the same as the M33 shot.

The nice thing about 5 minute exposures is that I have a lot of darks and bias frames from previous outings.  That means I can get to processing immediately after I take my flat images.

So after looking at these two images and thinking about a comment someone made on Cloudynights about shooting at least 6 hours on a target, I decided to really collect a lot of data on a fainter galaxy.   My target was NGC 925 which is located in Triangulum, the same constellation that contains M33.

As the galaxy is relatively small, I opted to forgo the focal reducer and shoot at the native F/8 of the Tak 102.

Shooting at F/8 presents its set of challenges.  Being used to F/5.6 on the 80mm scope and F/6.4 on the Tak, I had to shoot longer exposures.  I opted for 10 minute shots.  Over the course of 4 nights, I collected 80 shots and Deep Sky Stacker culled the best 72 minutes.  I also used 160 darks, 40 flats, and 120 bias frames.  It took me 3 days to get those darks!

As the single frames were coming in, I thought it looked promising:

But honestly, I thought the final stacked image had A LOT of noise considering the 720 minutes (12 hours) of data!    In a way, I consider the NGC 925 shot a failure.   Where is all the detail?   I know part of the issue is that about 1/2 of the frames came in at 22-29 degrees celsius.  I had one warm night (in the low 50's) that seemed to wreak havoc on the sensor.   I suppose I should try re-stacking only the cooler frames (below 20 deg c) and see if I get anything better.   

The other issue here might simply be scale.   On Cloudynights, there was a guy recently who shot this same target with his 8" F/8 Ritchey-Chretien scope.   Although he only shot around 5 hours, he got tons more detail in the arms of the galaxy.  So, that makes me think that I was just shooting the wrong focal length.

"We're gonna need a bigger boat."