Starting out in EAA - A journal of sorts... (UPDATED 18th October)

[Davesellars]

A bit of background:  I'm a visual observer and greatly enjoy using my 12" dob but since July I've mainly turned to using the 4" refractor for most sessions as I've had a few issues with my back.  My main interest are deep sky objects, but I've been really enjoying planetary viewing with binoviewers the last couple of months and no EAA would replace that.    After putting an RA motor on my EQ5 I decided to delve back into a bit of AP (sold my NEQ6 and imaging stuff back in 2017) with the DSLR but decided quite quickly that wasn't really my thing and got bored quickly without a real result until you stack them all and process (far too time consuming too!).   Still, I wanted to see deeper and further than my visual instruments will let me and also be able to share the night sky somewhat easier with my family (have 3 daughters, two of which are really interested and the other is too young atm).  my wife also loves looking at the DSOs and planets etc but doesn't like the freezing cold so much that comes with it...

So, I bought a ZWO ASI178MM mono camera. Pixel size seemed to match well with the focal length of my refractors 600 and 714.  Why mono? It's considerably faster and I'm not that bothered about colour and first priority is speed of getting a good image on the screen.

I've had a couple of short opportunities now to use my newly acquired camera using SharpCap with my 80ED.  1st night was with M13 (starting on something easy!) and then moved to the nearby galaxy NGC 6207.  M13 was amazing.  Within a few seconds it had surpassed with the 80mm aperture what I could see visually with my 12" dob.  The core was intense - the camera was certainly one hell of a lot more sensitive than my DSLR.   NGC 6207 is a small but relatively bright galaxy measuring only 3.45' x 1.6' and this I would generally have no problem seeing with the 12" dob but with the 80ED would need very good transparency to be able to "easily" see it.   With the camera and using 8 second exposures (gain I think was around 150), the galaxy was immediately visible and then started to show quite nice shape and further clarity after a few minutes.  Much more was immediately visible than with the 12" dob for sure being able to make out the shape of the galaxy extending further than its bright core.

I realised after this that stars were bloating quite easily due to the lack of an IR filter in the camera - so I purchased an Astronomik IR-Block for use in the second session.  While I was at it, I also purchased an Astronomik 12nm Ha filter as this would help considerably see some of the nebulae that are otherwise invisible in Bortle 5 skies.

Session 2 was on 10th October - Full moonlight!   I could make out Cassiopeia naked eye and using the 60mm finder found the position for NGC281 (Pacman Nebula) and started initially with liveview on 30 seconds which brought up nebula reasonably well.   This is where my knowledge of my camera started to lack regarding Gain and Brightness (offset) in Sharpcap...  Initially I was struggling to get the histogram peak sufficiently off the left-hand side and in the end boosted the gain to 300 and 60 second exposures with the brightness set to 0 (still no idea what I really should be setting this to...).  I fired of a set of 10 darks to apply first (I haven't got the hang of how to do flats yet).  I think the darks worked reasonably well although didn't seem perfect but certainly improved the live stacking process.  This is a big learning curve.  Anyway, the Pacman appeared really quite nicely after 3 or 4 frames and continued to improve.  I'd say after 15 frames the difference wasn't quite so significant from 15 to 30 frames - but that's when I stopped at 30 frames and saved the image as is...

 

So, I'm quite impressed with this little camera...  I'm looking forward to picking up much more small-medium size Ha targets as well as galaxies, globs and planetary nebulae.

Here starts the journey - hopefully I will append to this thread as a "journal" as I continue...

Edited October 18, 2022 by Davesellars

[glafnazur]

Great report,  sounds like a good beginning on your EEA journey. I look forward to reading more. 

[Steve in Boulder]

Excellent start, and I think you made some great equipment choices.  I have a 178MM myself, darks are important.  It looks to me like yours may have been slightly mismatched with the lights, because I see some traces of what might be amp glow in the corners.  This page from ZWO shows the amp glow pattern for the 178MM, which is what I see as well.   

60 second subs and gain 300 were good choices for your NGC 281 (with the Ha filter).  Offset should be non-zero.  I don't recall what the appropriate value for the 178MM is offhand, but the ASCOM driver will show ZWO's recommended value.  If you aren't able to find that, I'll check next session and let you know.  

SharpCap is a nice EAA application, but for mono cameras I think Jocular is quite a bit better.  

[Davesellars]

Many thanks Steve!

Yes, amp glow was still showing with darks (but to much less extent).  I'm not sure where to find the value for the offset but I'll have a good look and see if I can figure it out!   I'll also check out Jocular (I've not heard of this before!).

Edited October 11, 2022 by Davesellars

[Davesellars]

Ok...  I had to download the ASCOM ASI driver as I was just using the native ZWO driver.  From this in ASCOM diagnostics when i set either preset high or low gain it gives the value of offset to 340 (in the centre).  Does this seem about right?

[Steve in Boulder]

46 minutes ago, Davesellars said:

Ok...  I had to download the ASCOM ASI driver as I was just using the native ZWO driver.  From this in ASCOM diagnostics when i set either preset high or low gain it gives the value of offset to 340 (in the centre).  Does this seem about right?

That rings a bell.  I think that's ZWO's default (or recommended) offset value.  So I'd start with that.  It's a bit higher than other cams (my 533MM has a recommended offset of 70), but I'd still go with it.  An offset of 0 will lose data down in the blacks.  

[Davesellars]

Many thanks once again Steve!

[RobertI]

Lovely report and a great start to your EAA journey. Looking forward to following your posts.  🙂  I had a similar journey I think, finding imaging a bit too time consuming and having too much light pollution for effective visual of DSOs, EAA was the perfect solution. I also love the fact that you have a permanent record of your ‘observations’ and can share with others. I’ve just bought an ASI290 (my Lodestar finally konked out) and waiting for the right moment to get going with it

[Davesellars]

Many thanks, Rob!   Good luck with your ASI290 & looking forward to your first light report with it!

It will be interesting to see how difficult it is to actually find objects...  I've worked out that the FOV is approximate to looking through a Delos 14mm eyepiece with my 12" dob.  Fortunately, my sky is reasonably dark enough to make searching quite accurately with the 60mm finder fairly effective although I'd normally start with the 17.3mm Delos in the dob...  Using Liveview in Sharp at least shows up stars very well in near real time to make adjustments manually with the EQ5 and referring to SkySafari to hone-in on the object.

I have also setup Cartes du Ciel and using platesolving with ASTAP and so syncing my current position I have the possibility to see how far I am "out" to make an adjustment although I haven't had to use this yet, I tested this first inside using a DSLR capture from the previous week and setting the time correctly (there's nothing worse than trying to get things working for the first time out in the freezing cold!).  I then tested it while I was on M13 and after platesolving in Sharpcap the mount position synced perfectly in Cartes du Ciel.    This may come in particularly useful for the Virgo/Coma Berenices galaxies!

Edited October 12, 2022 by Davesellars

[Davesellars]

3rd Session!

13th October.  Approx 9 - 10:30pm

Scope used: SW 80ED.

Other: AS178MM & SharpCap stacking.

So, another short session...   Clouds yet again stopping play and transparency was mixed with lots of haze in areas.  However, progress I think has been made...

Around 6:30pm I had the scope out and pointed it at the dimming blue sky to take flats.  After a bit of experimentation and the light dropping fast, I managed to get the signal bang in the centre of the histogram using 3 second exposures.  Flats now taken - the camera is staying where it is now for the next session... .  I did have to move the focus a touch, but this made no effect on the suitability of the flats.   Using flats this time seems to have made a difference to the overall image being stacked in Sharpcap.

First up what M13 again to test out the darks & flats working together.  I had the exposure to 8 seconds and gain to 150.   Transparency/seeing was definitely not as good tonight as the FHWM was averaging around 4-5.  After around 10 frames this was excellent already, but I let it run some more to 37 frames as seen here (Taken as seen in SharpCap with histogram stretching only).

 

Next up was NGC 7331 in Pegasus.  This is a good size galaxy with prominent spiral structure and a fascinating for the multitude of galaxies in its group which I was hoping to capture more than NGC 7331 itself.   NGC 7331 is a nice easy target with my 12" dob for the relative brightness of the core but the structure is very difficult and needs excellent transparency to see any structure at all.   After a while, I think I got more much more than I expected as several other galaxies popped into view the lowest being a mag 15.9 with PGC 69281 (up and right from NGC 7331).

The galaxy structure was showing quite nicely after 5 minutes of live stacking with the other galaxies evident also.  I'm sure on a better night this would be improved (The transparency in this area of the sky was getting quite bad).  The above image is from 40 frames @ 30 seconds exposure with gain set to 150.  20 minutes and the structure is really showing very well indeed (much more than I expected from 80mm aperture).

 

Last up Stephans Quintet (just a very short hop from NGC 7331).   With the failing transparency and haze getting thicker I didn't expect that much and the below image is from 11 minutes integration (30 second exposures with 150 gain) before clouds swamped the sky entirely...

It came out better than I expected at least with clear splits of all the galaxies in the group!  I don't think I'm going to get any more detail from this group though with this small scope!

That was it for this evening!  Hopefully next time it won't be cut quite so short (again)!

 

Edited October 14, 2022 by Davesellars

[Mike JW]

Hi Dave,

Really impressed with your results - your imaging knowledge certainly helps. Enjoy the journey.

Mike

[Davesellars]

Many thanks Mike!  Nice to know I'm going in the right direction...

I'm wondering if perhaps my 120ST may be actually more beneficial to put to use for EAA.  Its extra light capture and resolution plus at f/5 I think may actually do a better job than the 80ED for galaxies and nebulae at least.  Now I've got a good reference with NGC7331 taken last night, I shall have to compare...

 

[RobertI]

Great results for a relatively  diminutive 80mm! Looking good. 

[Davesellars]

4th Session!

17th/18th Oct - Approx 9pm to 4am.

The promise of a clear night according to ClearOutside actually came true (which was nice).  Although it was evident early on that the transparency was far from good, I'd had the 12" dob for visual observing out as well as the 80ED on the EQ5 for some EAA.

I'd been referring to the Caldwell catalogue for some inspiration of targets.  1st up was the face on galaxy IC342.  This was very faint!  I'd taken darks at 30s and 150 gain so stuck with this although later I felt that this needed 1-minute exposures - it needed 5 minutes to really develop properly and by the end (50 minutes) I think it turned into a half-decent image showing some good detail in the spirals.  While it was doing its thing I setup the dob and went in for a cup of tea...

 

 

Next up was a the relatively bright galaxy in Pegasus:  NGC 7814.  Conversely to the previous - this is a straight-on view of the galaxy.  The galaxy showed immediately very well after the few couple of exposures (same settings) and then I let it develop for 67 minutes.  While it was doing its thing I trundled about a few objects with the dob (including this galaxy)  The transparency really wasn't very good though and while the galaxy was visible it was extremely faint and wouldn't take any magnification at all otherwise it was lost.

 

Then a change...  I popped switched the IR-block filter for the Ha 12nm and re-took darks.  Exposure time was kept the same at 30 seconds but upped the gain to 300.   Here, I'd like to demonstrate the difference between a short integration time (1st example is 4 minutes) with a longer one (second example is 35 minutes)

Above is 4 minutes only - I was surprised at how much the nebula showed with just this time especially for Ha.  OK, it's not that clean - but the majority of it is there...  Compared to below:

 

Ok, so quite a bit brighter, cleaner and some more detail on the periphery of the nebula and I think the main difference is that it started to gain quite a bit more depth to the image.  Still, only 36 minutes of total time is small for a Ha target so I was really happy with this result!  I think the banding seen is perhaps from the extra gain used (300) over the images taken at 150 gain for the previous galaxies.

So next up had to be another nebula (being in the area already!) and chose the Bubble (NGC 7635).  Again, I chose 30 second exposures with the same gain (300) but this time I switched to binning x2 and this nebula showed immediately to great effect.  I let it run though for 58 minutes while I spent quite a bit of time with the dob viewing Jupiter (seeing so-so) and Mars.

Now was time for a bit of testing to compare the above with a shorter integration time but longer exposures - to 1 minute (didn't bother with darks here so please excuse the amp-glow noise!).    Below is only 6 minutes (12 frames)

The stars still seemed reasonably round so i pushed my luck to 2 minutes exposures but dropped the gain to 250.  Below is 8 frames (16 minutes total)

 

Really, comparing this and the first I don't see that much difference in detail.  Ok, I'm obviously pushing it with 2 minutes unguided on an EQ5...   But, it's not too bad and the FWHM was confirming that it hadn't increased that much and so was acceptable (this is not a polished AP image after all).  I think if I can really get my polar alignment dead on (it's very close!) and ensure very little flex there's no reason why I can't continue with 2 minute exposures for Ha targets.

Orion was nicely positioned now so switching taking the Ha filter out for full spectrum again I went for M42 for very short exposures (4 seconds).  Below is just 5 minutes integration time (it was getting very late!)  I took some darks first as quick to do with only 4s exposures.

 

 

The nebula is massive so does not quite fit the frame (majority is there though!)

On quickly to the Flame nebula....  Only 4 minutes of 30 second exposures but starting to show really nicely....  I am assuming that the artifact around the bright star is the result of dew?  I didn't have any issue earlier in the night with an equally bright star.

 

 

Then quickly again to the Horsehead...  6 minutes of integration with 30s exposures.  The reflection nebula is showing really well already and the Ha coming through defining the HH.

 

That was it...  I was thoroughly frozen...   and it had turned 4am so it was time to call it a night with everything dripping wet.  Hope you've enjoyed this "journal" log....  I am still learning!!!

 

Edited October 18, 2022 by Davesellars

[Mike JW]

Hi Dave - you are on a roll. I remember those days of long sessions - not for me now (age!). Lovely set of results and such a good idea to do visual on the Jupiter at the same time.

Thought you might like to see my attempt at the Bubble Neb.  

Using 7" of aperture meant I could keep time down to a minimum but still get worthwhile results. Personally, I generally aim for 5 mins or max of 10 minutes to keep it vaguely 'live'. As a working figure, there seems to be little improvement beyond about 30 subs unless I go after something very faint. Maybe I should visit the Bubble with my large Dob.

I shall keep watching your posts with interest.

Cheers,

Mike

[Davesellars]

Many thanks Mike!  That's a great result on the Bubble from before for such a short amount of time.  I assume that was without the use of a filter?

I think my main restriction for getting bright objects quicker is obviously the aperture of the scope here so it will be interesting to see what difference there would be using the 120ST instead of the 80ED.  So far, the sky is looking good so I may give it a go later to compare if it stays clear.  I would be nice to get results faster but I've found pretty much the same that after a certain amount of frames there is very little real increase in detail apart from the image getting cleaner and perhaps a bit more fuller.

[Davesellars]

Ok, just a quick one...   Have the 120ST out tonight but conditions are pretty dire.  I've managed to capture C/2022 E3 (ZTF) though even through the murk!

[Mike JW]

Hi Dave, I thought about the comet but the sky was rubbish in that direction, so good for you for giving it a go. 

I took a look at the bubble nebula but this time with my 15" Dob - see the post as above.

Mike