Steve in Boulder

Since this is EEVA, start with SharpCap’s gradient correction tools.

Very nice, I particularly like NGC 2146 and NGC 1501.  For larger, fainter PNs like the Headphone Nebula (Jones-Emberson 1) and Abell PNs, a dual narrowband filter can be helpful, although you’ve certainly captured it as is.

18 minutes ago, AKB said:

Thanks for that.

Interesting, I’ve never used my 294MM in that mode (which would also receive four times fewer photons), but always binned x2.  

Everything's a trade off!

Tony

At f/2 you might be able to afford less photons per pixel!

What a great set of views!  That RASA/294MC combo works nicely.   I’d guess the SNR advantage of mono over OSC would be about sqrt(3), or ~ 1.73 times.  But color has information too, like the H-alpha filaments in M82 you captured so nicely.  

One other consideration is that a 294MM would give a pixel scale of 0.77”, twice what you’re getting with the 294MC, so depending on seeing you might get better detail.  Even a 533MM/2600MM (or MC) would give a 1.25” pixel scale, which might be a good match for your seeing.

Whenever I see a star near a galaxy in an EAA image, I always check Aladin.  Keep hope alive!

Thanks, that was helpful!  I was much better able to orient myself.  I loaded the FITS into ASTAP and annotated it via SIMBAD.  One thing I noticed is related to the bright, but not as bright as HD 65601, star at the left.  If you look at the same position angle from it as your object is from HD 65601, you'll see a similarly shaped, but smaller object.   That object doesn't appear in PANSTARRS.  This makes me think that both objects were caused by something with the optics near a bright star.  

3 minutes ago, Richard N said:

They are automatically scaled and matched by Aladin. 

Well, I'm still a little confused by your image, because comparing the two there are brighter stars in PANSTARRS than the brightest star other than HD 65601 (at the top) in your image.  In any case, if you zoom into PANSTARRS DR1 on Aladin Lite at the given coordinates, you can see a faint wisp that isn't identified by SIMBAD.  So potentially a galaxy and a supernova.  

They don't seem to be scaled identically - the galaxy in the PANSTARRS image is closer to the bright star (HD 65601, I think) than the object in your image.   I'm having some difficulty matching the two images - is it possible that yours is reversed?   In any case, looking at PANSTARRS DR1 on Aladin Lite, I see a star right next to the nearest galaxy (LEDA 2621212).  It may be obscured by the "Galaxy" label in your PANSTARRS shot.  

Hi Dan - As stated in the documentation, Jocular should be run on Python 3.6 to 3.9.   I would start there.  

1 hour ago, CHR15 said:

Thanks.

Yes I'm using an achromatic refractor. What filter should I use for the bloating? The last photo is the ET cluster (ngc457).

I shall try using flats. Is bias the same as taking darks but with the quickest exposure possible? 

These were all using the auto histogram on the asiair plus app. I'll have to have a play with the histogram.

I have added the equipment above and the exposure times we 50 x 10 seconds for the galaxies. The stars were only single short exposures. 

What does the gain do?

Yes on bias.  You want the camera to be in total dark.  

The auto histogram on the ASIAir app is a good starting point, but you can do a lot better manually.  Expand the histogram using the button on the right.  Typically you want the black point (left slider) to the left of the histogram peak, and the right slider (mid point I think, not sure because ASIAir docs don't say) pushed to the left enough to show the features you're looking for.  

Unfortunately the ASAir app doesn't have hot pixel correction, so you'll probably want darks.  The dark sub exposure time should match your lights, i.e. 10 seconds.

1 hour ago, CHR15 said:

Thanks.

I've edited the equipment above.

I will try doing some flats next time to lose the vignetting.

I've read that my camera has zero amp glow. Does that mean I don't need darks?

The second to last photo is Dubhe. It was pretty much at the zenith, it was in eq mode rather than alt az mode.

I used a bahintov mask to try and focus, maybe too long exposure time on a bright star for photo number 9.

The galaxy photos were around 50 x 10 second exposures.

As Martin mentioned, darks are also helpful for hot pixels.  You can tell if they're a problem by looking for little streaks of color.  As also mentioned by Martin, your live stacking software may have a hot pixel correction feature.

It's helpful to know the gain as well.  Here's a useful explanation about gain.  50 x 10 seconds is a bit more than 8 minutes, which is a typical amount for EAA but you do have to expect some noise, especially if you stretch aggressively to show fainter features.  And by the way, aggressive stretches will emphasize vignetting, all the more reason for flats.  

For the Dubhe photo, perhaps your polar alignment was off?  

And I forgot to say, excellent images for your first effort!  

Flats should be a high priority.  There seems to be moderate vignetting, which flats will help with immensely.  Darks depend more on your camera's (you didn't specify which one) amp glow (aka dark current or thermal noise).  

The second to last one has elongated stars.  This could be the result of imaging near the zenith with an alt-az mount, if that's what you use. 

I'm not sure about your focus in images five through seven.  Do you use any focusing aids?

Noise is directly related to total integration time (number of subs x sub exposure time).  You haven't listed those, so it's hard to say more.  

2 hours ago, Odiug said:

Ah, yes. Thanks Seve. I guess, I need to practice more. But I definitely need smaller subs.

With a 294 camera you may want to bin 2x2 or even 3x3, especially while you're learning the controls.  Also, you may get better performance by turning off continuous updating for the sliders.

I think performance enhancements for larger sensors are under consideration by Jocular management.  

6 hours ago, Odiug said:

I am trying to use Jocular with Kstars/EKOS. Images are FITS 16bit RAW from an ASI294mc. Fits header shows:

SIMPLE  =                    T / file does conform to FITS standard             
BITPIX  =                   16 / number of bits per data pixel                  
NAXIS   =                    2 / number of data axes                            
NAXIS1  =                 4144 / length of data axis 1                          
NAXIS2  =                 2822 / length of data axis 2                          
...
BAYERPAT= 'RGGB    '           / Bayer color pattern                            
...

In Jocular under "set up devices" "color space" I selected RGGB. In "channel chooser" I selected RGB. I still see a grey scale image. "filter(s) chooser shows "B", but I cannot change it.

What am I doing wrong?

Regards & CS

Guido

Hi Guido -- The first thing is to stack the images!  Your screen capture is a view of a single sub.  Click on the icon on the top that looks like a stack.  It's under the number of the sub.

9 minutes ago, LaurenceT said:

Excellent, I do have an Apple TV module, I just need to work out the networking implications as the Ipad would be on the Asiair network.

Yes, you might need to put the ASIAir in station mode so that everything is on the same WiFi network.  But I think that would use the much slower 2.4GHz WiFi, not much fun for EEVA.  Worth trying!

If you have Apple TV then you can use screen mirroring.  Other smart TV devices might have something similar. 

1 hour ago, Martin Meredith said:

I may not have transferred all the doc across to readthedocs, but it is described in the older version of the docs here: https://transpy.eu.pythonanywhere.com/jocular/#

Essentially, ROI applies to the view you see in the 'eyepiece' at the point at which you click the ROI icon, and continues to apply until you click ROI again. The only thing to be careful with is that there are enough stars for stacking purposes, since ROI throws away anything not in the view. 

This is the relevant passage:

Jocular implements region-of-interest (ROI) as follows. First, use a framing capture and the pan/zoom/rotate options to get the object just how you want it. Then stop the framing capture and click on the ROI icon. Any subsequent captures (for the current observation) will be restricted to that region. Click ROI again to see the full sensor. Note that currently you need to set up any binning options *before* choosing the ROI.

 

 

Martin, does this feature work with a "watched camera"?  I think Dan captures all his subs with TheSkyX and uses Jocular in watched folder mode.  His camera has an enormous sensor, so I think he's trying to keep memory usage down.  

1 hour ago, catburglar said:

I suspect it’s because the orientation of the view is flipped - so you’d need to change that in the view settings…but not sure if that just affects the new images or the entire stack-in which case you’ll still be snookered I suspect…

I feel like this has a shot.  The combination of a top-bottom flip and a left-right flip is a 180 degree rotation, which is I think what happens with a meridian flip.  So toggle both flip switches.  

Can you try turning the gain down a little?  400 is the max value, perhaps that's causing a problem.  With the 178MM, gain 200-300 is probably preferable for EEVA.  At 400 the full well value and dynamic range are very low (bad).  At gain 200, read noise is almost as good as at 400, but much better full well and dynamic range.  You can see the graphs here.

49 minutes ago, Davesellars said:

Many thanks, Martin.

That's a little clearer!  I've now connected the camera and set gain and offset with an exposure of 2 seconds with the cap open on the telescope (testing during the day...)  and clicking on the camera icon which then goes green but nothing is being displayed...  I've used APT to ensure that something would be displayed and it's fine there...  What could be the issue?

Do you see anything happening in the 'capture' line in the status area (lower right hand side outside the circle)?  And just to be clear: when you say you've connected the camera, you've both selected "ASI Camera" and clicked the "connect" button?  

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.  

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.  

3 minutes ago, Mike JW said:

Hi Steve,

No problem posting this side of the pond. Rather a fine set of captures and I like your idea of showing an object using different filters,  although I am not sure of the significance of the different filters in terms of what it reveals about the particular DSO. Martin/myself tried to set up quite a few threads to cover different DSOs, in an attempt to keep observations together. There is a thread for PNs - Planetary Nebulae EEVA style.  Also where possible it is good to add observational details, rather than simply post an image (hence my interest in your images with different filters). By adding observational details, facts, maybe links to research papers it then makes EEVA more worthwhile through the encouragement to observe, learn about the DSO - in contrast to posting an image and not making any observational comments.

I shall look forward to your next observations.

Cheers,

Mike

 

Thanks, Mike!  I’ll try to do better to adhere to that protocol when I post again. 

Oops, that was the OIII view for Abell 71.  This is better:

And a couple of oddballs, again in HOO and Ha views.