Martin Meredith

Agreed, an excellent intro that will be very useful to anyone starting out in EE(V)A. Martin

That's a lovely grouping. The surrounding star field seems to have formed a circular window thru which to view SHK 361.

Glad you reminded us of the Hickson 93 designation as I couldn't find it under my Arp collection... What I find fascinating about NGC 7549 is the appearance of a sudden drop in intensity along the upper arm as if there's a discontinuity of some kind. I also recall thinking when I looked that the lower arm looked somewhat 'frayed' but I suspect these are artefacts. Here's a close-up from last year (which doesn't add much if anything to your shot, where your better resolution shows up in the various 'knots' along the bright arm) Martin

I agree, a wonderful write-up and a lot of links I'd like to follow up when I have more time. It goes to show how much fascinating stuff there is in some fields. As an aside, I've often found myself wondering about why sometimes in EAA we spend so little time on each field (trying to differentiate EAA from AP, I suppose). Even with my small FOV there are too many objects to properly appreciate in a short time, and with the larger FOVs that are becoming more widely-used in EAA one could easily spend an hour or more on each field. Martin

I found that I had to update the drivers (for the cable) to get my AZ EQ6 to talk to my laptop using EQMod. This is with the Lynx Astro cable. Martin

Excellent result! Much better than my first effort... The blockiness might be due the Lodestar's large pixels combining with a short focal length, resulting in undersampling. What was the FL of your refractor? I have a 77mm f6 refractor and sometimes see blockiness on nights where the seeing is good. As for the blockiness appearing to increase with each new sub, it might be simply that the SNR improves and the blockiness becomes more evident? Martin

I don't have a cooled camera so my approach is to collect darks at various points during the observing season (certainly not every time I observe) and note the ambient temperature (and duration, of course). It doesn't take too long to build up a darks library in this way and so long as you also note the ambient temperature for your lights you can reuse such darks many times. Martin

Simply stunning! Martin

Binning is one way to resize, but is generally suboptimal compared to the interpolation used in most resizing algorithms. Binning is convenient for sensors as it doesn't involve anything very complicated. In technical terms, resizing downwards (downsampling) involves losing resolution i.e. high spatial frequencies. If you just bin, then the energy represented by those high spatial frequencies is still present in the image, but is spread around as noise. Proper downsizing ensures that the high spatial frequencies are attenuated first, so the image is just a little bit less noisy. Most likely it would be hard to spot much difference except in some edge cases, but since most resizing software already takes care of this, I wouldn't recommended binning. cheers Martin

I thought on a thread dedicated to the VV catalogue it would be a shame not to include the first one in the list: This is also Arp 85. This one is not oriented N as that would place NGC 5195 right above M51 which looks ugly. I've marked three objects that are in the Milliquas quasar/candidate catalogue. The mag 17.1 one has a 66% probablity of being a quasar apparently but there is also a variable star with a 28-day period at the same location so who knows. The mag 19.2 quasar has a prob of 95% and is somewhat brighter in the red filter. The mag 20.7 quasar that I think is just about detected here has no red shift listed, has a prob of 80% and is again brighter in the red (mag 18.9) which is no doubt why I might have picked it up. The bit of fuzz labelled IC 4278 apparently is 10 times further out than M51/NGC 5195. The unlabelled thin slash of a galaxy to its north (in this shot) is IC 4277 but I've not been able to find out much about it. Martin

Thanks Jeremy. its always fun to look at several in the same session. If nothing else its a reminder that not all globs are the same! Martin

Very useful video Curtis. In my own case I recently replaced a heavy car starter battery by the Bresser portable supply which by comparison weighs next to nothing and takes up hardly any space: https://www.skyatnightmagazine.com/reviews/accessories/bresser-portable-power-supply-100-watt-review/ Martin

Here are a few globs from last night. They are all from quite low altitudes so highly reddened. Scale is same apart from the last shot. And finally, our old favourite sparse cluster, Pal 5, of which there are lots of images further up the thread This shot has the 1.8 billion light year galaxy cluster Abell 2050 in the top left corner (some galaxies can be made out). Distance estimate to Pal 5 is around 75k light years, so the galaxies are about 25000 times as far away as the globular cluster. Martin

I finally managed to complete my observations of the Berkeley open clusters on Sunday. Now comes the job of assembling them all into something coherent.... I feel some automation is needed. Meanwhile, the most interesting of the last batch (of 4) was Berkeley 55 in Cygnus. This is a compact, highly-reddened cluster located about 4 kpc away in the Perseus Arm, and which is estimated to be pretty young (~50Myr). The most interesting feature is the obvious cluster of bright red stars. This paper https://arxiv.org/pdf/1112.0414.pdf looks at the cluster in detail with optical and spectroscopic observations from La Palma, and identifies the 6 or 7 red (super)giants clearly visible in the image. Out of interest, I created some finder charts using GAIA stellar data during the Berkeley campaign as some of them are quite hard to spot. Here's the one for Be 55. It is pretty remarkable how similar it is, and slightly depressing too, as it somewhat ruins the surprise.... cheers Martin

I'd forgotten that M82 is also Arp 337 It is categorised as 'unique' within the Arp catalogue and it is easy to see why. I've also marked three quasars. These are known (from top to bottom) as Hoag 1-3 and have the distinction of having almost identical redshifts (as marked), leading to the controversy over whether such similar redshifts could have occurred within such a small grouping by chance. (Nowadays there are more than 2 million quasars catalogued so it isn't such a big deal, I guess). Anyway, back to the observation. I think I've only managed to pick up Hoag 1 and possibly not even that, but I would hope others will have a go at detecting these three.

I had a chance to observe a further 8 PNs last night, all in Cygnus. They came in various shapes and colours, and some of them are very hard to spot indeed in the 'wide' field images (0.34x0.44 degrees here). Here's NGC 7026, which is a very pale pinky-blue. The bright star in the image is 63 Cyg, mag 4.5, which is double (sep 15") and slightly variable. A closer look at the PN shows two bright parallel bars, joined by wispy material at each end (the Hubble shot provides quite a bit more detail ;-). I also included the beautiful unequal double, Burnham 158, at the right of the shot, mags 7.5 + 12, sep 11" and turned up the colour saturation to better appreciate the contrast. Martin

Nice shot and write-up. I'm quite taken by the little cluster of stars to the SSW. Looks like a couple of optical doubles at least. It is interesting to visit the same things on successive night just to see how much seeing affects the view. Martin

Lovely shot. I just looked this one up in the de Vaucouleurs atlas where it figures as a luminosity class I-II standard for Sb galaxies. The image shows an extensive and quite messy set of spiral arms extending 3-4 times the width of the central 'theta' part in your shot. I imagine this is one of those galaxies that just gets progressively more detailed with increasing overall exposure. Martin

That's a great-looking group. I wonder how accurate the distances are? Perhaps at that distance 50 million LYs is within the range of error. Having said that, the group does look bimodal in terms of brightness. Martin

Fascinating object, whose interpretation is much aided by the diagram. Definitely a candidate for the Spot the PN competition that we don't yet have.... I've only got one supposed observation of a 'K' object, K 1-13, which remains invisible in my shot (without filters). Martin

I had this problem of not seeing the COM port recently with a new Lynx Astro cable with direct PC to mount connection and the solution was to update the (FTDI) driver. Not sure if this is your issue but it solved it for me. Martin

Garfinkel's Star Hopping also covers a surprising amount of mythology. Martin

Thanks for the offer James. I'm not sure it is worth you making changes but perhaps oaCapture can already e.g. output the RGB as 3 separate frames, or output as a single 2D fits prior to debayering (I assume oaCapture is doing the debayering)? I'll push ahead with the next release and try to get it done in the next couple of weeks (its a rather large update, mostly completed, but many things have changed internally to handle the capture side so it needs a lot of testing by me before springing it on the world at large). Martin

That FITs output by oaCapture is also 3D (ie 1980 x 1080 x 3) so still not in the format Jocular can (yet) handle. Martin SIMPLE = T / file does conform to FITS standard BITPIX = 8 / number of bits per data pixel NAXIS = 3 / number of data axes NAXIS1 = 1920 / length of data axis 1 NAXIS2 = 1080 / length of data axis 2 NAXIS3 = 3 / length of data axis 3 EXTEND = T / FITS dataset may contain extensions COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H DATE-OBS= '2021-05-27T09:54:55.306' DATE = '2021-05-27T09:54:55' / file creation date (YYYY-MM-DDThh:mm:ss UT) COMMENT Input Frame Format: RGB24 (24bpp colour) XORGSUBF= 0 YORGSUBF= 0 FILTER = 'None ' SWCREATE= 'oacapture 1.8.0' EXPTIME = 0.01 ROWORDER= 'BOTTOM-UP'

Just wondering (maybe James knows the answer): is the 290 the Altair version of the ASI 290? If so, maybe it will work natively with the ASI driver I'm looking to incorporate in the next version. Or perhaps I'm being hopelessly naive. Martin