At the end of an eventful day...

[AKB]

On the day that the event horizon was imaged, I just had to take a look at M87, and so my evening started around 21:30 with this target. 

I've not viewed it before, but taken note of @London_David's thread here:

After a good look there, I moved on to others recently added to my Jocular observation list (love the way that works!)

With super-massive black holes in mind, I moved to M60 (and M59 plus others.)  Wondering whether this is on the list for future EHT images?

Next, NGC 4567 was actually I target I just picked off Stellarium being in the general area (and I liked the number), which of course is surrounded by other satisfyingly fuzzy targets.  I have to confess that The Hyperstar/Ultrastar camera/scope combination, plus all the recent posts here have whetted my appetite for some of the less-known, and perhaps more interesting objects, rather than just the 'chocolate-box' ones.  So thank you to all here for that!

M99 and then M98 also captured my attention, but then, beyond them, more intriguing objects.  Where best to read up on all this?  My interest in astronomy has been lifelong, although my practical involvement is much more recent.  Good charts will no doubt help.  I've recently also purchased a (paper) copy of "Illustrated Guide to Astronomical Wonders", although that is more for visual observing, but it does, at least, take you off the beaten track a little way.

I returned to M87 at the end of the evening, wanting to zoom-in and repeat others' success at seeing the relativistic jet.  The best I could do wasn't very good.  I don't think that, in this case, the scope/camera combination is particularly appropriate.  It was a bit tricky to find the right levels, and number of exposures to use.  My experience after some trials, was that it really doesn't matter.  This is a bright target on a similarly bright background, a short sub will do it, a long stack doesn't help much.  On my pixel scale, though, it is a bit small.  But it was there – in the end I've posted a single 20 second sub – not much to show for something 5000 light-years long, but exciting, nonetheless.

The seeing overall didn't seem to be that great, and it was still a little windy.  By the midnight, everything was covered in dew, which surprised me because the humidity had been very low during the day (OK, I do know about dew point, but I just was hoping it wouldn't come to that.)  I'm sure others observing last night went on well beyond midnight, but I didn't have the stamina.

Today, I've taken the bold step to remove the Hyperstar and switch to a x0.63 reducer, so moving from F2.3 to F6.3, for a closer look at some of there distant delights.  Thanks for any thoughts on the above.

Tony

 

 

 

 

 

 

[Martin Meredith]

Nice shots -- a mini Messier marathon.

It looks like you have sussed out calibration frames in Jocular!

Just on that, in an earlier pre-release I had an automatic recompute threshold, mainly to solve the following 'problem': if you are relying on J to estimate exposure based on time-of-arrival differences, it can't know the exposure until at least 2 subs are in, and at that point can select an appropriate dark to apply. Having an automatic recompute meant that by sub 2 J would know which darks to apply to sub 1 and would do it automatically. That no longer happens for reasons too long to go into now, but I hope to reinclude this behaviour in  a future release. The upshot is that you might think it is applying darks but isn't until you hit the recompute button manually....

Martin

[AKB]

27 minutes ago, Martin Meredith said:

It looks like you have sussed out calibration frames in Jocular!

Well, I thought I had, but reading further, then perhaps not!

So a recompute any time afte4 the second sub will do the trick?

[Martin Meredith]

48 minutes ago, AKB said:

Well, I thought I had, but reading further, then perhaps not!

So a recompute any time afte4 the second sub will do the trick?

That's right. Tedious I know and something I will sort out...

[Mike JW]

Hi Tony,

Just enjoyed a second read and look through your post. Interested that you have removed the hyperstar. I find the fast, wide angle, tight stars of hyperstar shots fascinating and have been wondering about buying a hyperstar for my C9 but in the end I decided I like the flexibility of using a 0.5 focal reducer. If I wish to get a slightly wider shot I adjust the distance to get f4.4 or even a touch faster. Sometimes I go the other way and use it at f5.5 (current favoured compromise setting). If I am going for the small faint stuff I am not adverse to using the scope at f10. I use to have a f6.3 reducer and sold it, probably should have kept it and then adjust the distance to the chip to operate between f5.5 and f 7.  A final advantage of using the 0.5 reducer is that I can be doing visual and then easily switch to a spot of camera work. The f6.3 reducer was great for the same reason.

Mike

[AKB]

12 hours ago, Mike JW said:

Just enjoyed a second read and look through your post.

Thanks for that!

12 hours ago, Mike JW said:

Interested that you have removed the hyperstar.

I used to remove it every time after an imaging session, but now it stays on for weeks at a time.  Only problem is no proper dust cap when it's attached, so a plastic bag over the end does its best, but I don't like to keep it that way for too long.  Yes, I'm wanting to get a bit closer to those galaxies, but with a switch of camera to an ASI294, then it's not actually a smaller FOV.  I'll move to F10 later.

Checking out the setup this evening just after 7.00 PM before the clouds rolled in, so here's a definite EEVA image... 1/1000 sec!

[Mike JW]

Lovely. Makes me want to get back to lunar sketching. Life is too short! Mike