What can be done with just ~25 mins of data

A place to share images that you have taken with SharpCap.
Forum rules
Please upload large images to photo sharing sites (flickr, etc) rather than trying to upload them as forum attachments.

Please share the equipment used and if possible camera settings to help others.
Post Reply
NeilG
Posts: 78
Joined: Wed Feb 22, 2017 9:36 pm

What can be done with just ~25 mins of data

Post by NeilG » Sat Feb 22, 2020 1:31 pm

First light for my 2nd new ASI533 - the original had a fault and was replaced by FLO.
I just needed to do some tests - some lights, flats, darks and dark flats to prove that the fault seen in the first camera was absent.
So, here are 3 images all taken on 20th each using 12 sec exposures, gain 110. M82 and M95 total exposure ~25mins, M97 total exposure ~11mins.
Processed in Astropixelprocessor using lights, darks, flats and flat darks, and APPs default stretch.

I'm quite pleased to see the results - very promising for longer exposures. Now to go and play with the in Pixinsight (not tried out the postprocessing features in APP yet.

M82
ImageM82_St-avg-1536.0s-NR-x_1.0_LZ3-NS-full-eq-add-sc_BWMV_nor-AAD-RE-noMBB-St

M95
ImageM95_St-avg-1536.0s-NR-x_1.0_LZ3-NS-full-eq-add-sc_BWMV_nor-AAD-RE-noMBB-St

M97
ImageM97_St-avg-648.0s-NR-x_1.0_LZ3-NS-full-eq-add-sc_BWMV_nor-AAD-RE-noMBB-St
Scopes: Celestron C11, 102SLT , Ascension 127mm Apo, Opticstar 152mm Mak, Ascension 80mm Apo
Mounts: EQ8, EQ5 Pro, Nexstar SLT
Imaging: ASI1600MM-Cool, ASI533MC-Pro, ASI290MM, ASI224MC, Quark, QHY5L-II-M,
Opticstar 82 eyepieces, lots of other stuff

mAnKiNd
Posts: 303
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: What can be done with just ~25 mins of data

Post by mAnKiNd » Sat Feb 22, 2020 5:31 pm

Looks great, have fun!

User avatar
oopfan
Posts: 593
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
Contact:

Re: What can be done with just ~25 mins of data

Post by oopfan » Sat Feb 22, 2020 9:55 pm

Hi Neil,

Your scope, what's the aperture, focal length, and secondary mirror obstruction (if applicable)? I'll model it in software to calculate the signal-to-noise ratio of each image.

In your signature you list a number of different scopes. Which one was used here? Were you using a focal reducer?

Thanks,
Brian

NeilG
Posts: 78
Joined: Wed Feb 22, 2017 9:36 pm

Re: What can be done with just ~25 mins of data

Post by NeilG » Sun Feb 23, 2020 8:33 am

Its the 127mm Apo @f7.5 - no obstruction, no focal reducer. (oops - forgot to add these to the first message)

sounds like you have a useful tool fort SNR?
Regards
Neil
Scopes: Celestron C11, 102SLT , Ascension 127mm Apo, Opticstar 152mm Mak, Ascension 80mm Apo
Mounts: EQ8, EQ5 Pro, Nexstar SLT
Imaging: ASI1600MM-Cool, ASI533MC-Pro, ASI290MM, ASI224MC, Quark, QHY5L-II-M,
Opticstar 82 eyepieces, lots of other stuff

User avatar
oopfan
Posts: 593
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
Contact:

Re: What can be done with just ~25 mins of data

Post by oopfan » Sun Feb 23, 2020 3:12 pm

Hi Neil,

Here are the results for M82 given 12s exposures and 128 subs. I forgot to ask about light pollution, so here is a range:

Bortle 4: SNR 8.3
Bortle 5: SNR 6.3
Bortle 6: SNR 5.0
Bortle 7: SNR 4.1

Here are the definitions I am using:

Telescope
Name: Ascension 127mm f/7.5
Aperture (mm): 127
Focal length (mm): 952.5
Central obstruction (mm): 0
Total reflectance/transmittance: 0.99

Camera
Name: ZWO ASI533MC Pro (gain 110)
Pixel size (um): 3.76
Read noise (e-): 1.5
Dark current (e-/s/pixel): 0.0003
Quantum efficiency (%): 60

Target
Name: M82 Cigar Galaxy
Surface brightness (mag/sq arcsec): 21.24

My comments:
This calculator was designed for LRGB imaging with a monochrome camera. The SNR values are true for the L channel which is where the bulk of detail comes. A survey of AstroBin images taken with a monochrome camera show that SNR 25 puts you in competition for Image of the Day (IOTD). I ought to run a survey of OSC images to see differences if any.

To achieve SNR 25 in Bortle 5 skies you need to increase total integration time to 6.7 hours. If you increase exposure to 20s then you can achieve SNR 25 in 6.0 hours. Increasing exposure more will further reduce total integration time. Your camera has a Full Well Depth (FWD) of 50,000 electrons so you can go with much longer exposures before star saturation.

Brian

PS: Here is M81 that I am working on. I've got 9.1 hours invested in it so far. Tonight I'm going to make another run of RGB that should bring out the blue in the outer arms.

This is what SNR 25 looks like. It is bright. Taken with William Optics 71mm f/5.9 (not APO), camera Atik 314E (5.3e- Read Noise)
Attachments
M81_L250x90s_R47x85.3s_G50x50.2s_B50x77.8s_S15-3-25_SA30-25_G93_SGB2_SH70_2020-02-23_v2.jpg
M81_L250x90s_R47x85.3s_G50x50.2s_B50x77.8s_S15-3-25_SA30-25_G93_SGB2_SH70_2020-02-23_v2.jpg (390.18 KiB) Viewed 193 times

Post Reply