Fir Chlis

Another 585 user here - ZWO ASI585MC. Like you, I picked M81 and M82 on my first session with my new camera in January. You are right to be happy with your first go. Your M82 is really nice but, as I found as I learned more each session, you should be able to get better images of M81 as you progress. You could try using the SharpCap Brain function to calculate exposure time and gain - but set the maximum exposure time and get it to calculate a gain/offset setting. I now have fairly standard settings, but do use the Brain regularly to check things. For my camera it almost always comes out at gain 300 with 4s or 8s (gain range for the ASI585MC is 0-600). For myself, I find that darks do help, but I usually only need to do one set in an evening, unless the temperature changes very much, as I generally use the same exposure /gain all night long. At the exposure times I use, a dark only takes a couple of minutes to generate. I normally do a flat while it's still light, but I'm undecided about whether it is useful. I've still yet to try @PeterC65's suggestion of just using hot pixel removal. I now always use satellite trail removal and the automated brightness filtering, and am going to start trying FWHM filtering (though this may not be so relevant for a non-tracking mount). If you have a look at my recent thread on the SharpCap forum, I'd sorted out a procedure for myself to find the longest exposure that I could run before stars started trailing too much. How good is my mount? – improving EAA images - SharpCap Forums Exciting times ahead for you. After just doing visual, EAA opens up a whole new world. Geoff

Following on from this, I’ve done an analysis of my mount’s performance using sets of raw frames that I took a few weeks ago. As it is SharpCap specific, but the procedure may be useful to others, the write up is on that forum. https://forums.sharpcap.co.uk/viewtopic.php?t=7630 Geoff

With some downtime due to cloudy night after cloudy night, I’ve been researching guiding (PHD2) and PE training/ PEC and was wondering if anyone doing EAA uses either of these - and if they are of noticeable benefit in EAA. My suspicion is that they are probably too much of an overhead in lost observing time, especially if you get infrequent clear nights, and may not have any noticeable benefit with the relatively short sub-frames used in EAA. I know that, in theory, once a PEC curve has been recorded you should be able to reuse it, provided that the mount (HEQ5Pro in my case) is parked and unparked but the occasional crash /disconnect that I get with SharCap /EQMOD would invalidate and necessitate re-recording. Guiding, of course, requires the expense of another camera, and I’m guessing that there’s another overhead in setting PHD2 to guide for each object you want to observe, which is going to eat into the observing time. Cheers Geoff

Done. I should update my signature with my gear. 😀 Cheers Geoff

Nice pictures - and the stars aren't looking blobby now. Did you do anything different this time? Not sure when I'll get another clear night, and nights are getting shorter. Geoff

Very good. You've inspired my to go and have a look at my M87 from a few nights ago and, to my surprise, I've got it too! Here's a crop from my live stack of 39x8s frames stacked in SharpCap, just about visible emanating in the 5 o'clock direction from the core. Could do with a revisit to try for a better image. Some post processing might pull it out a bit better, but this is as seen. Skywatcher 200PDS on Skywatcher HEQ5Pro with ASI585MC, SharpCap 4.1 Geoff

Interesting shots - supernovae are on my todo list - as @PeterC65 has done, I’d like to monitor one over time. But so much to look at, so few clear nights. Geoff

This is the time of year when I'd normally be putting my scope away until September for visual observing, but now I'm doing EAA I'm hoping to be able to extend my astronomy further into the Summer (without losing too much sleep!), so I was wondering about advice /tips for EAA during the Summer months - e.g. suitable target types. I'm guessing that it may be the equivalent of going up a few Bortle levels. I'm wondering also whether to switch to more of an astrophotography mode, but using typical EAA exposures /durations, with the SharpCap Sequencer - e.g. capture a set of targets in the middle of the night, and then play back the raw frames with the Folder Monitor Camera to simulate a live session the next day. Geoff

Well, that certainly looks to have been a more productive session that mine last night. Some nice interesting targets/images there. I'd just discovered the Stellarium highlighting feature, and used it 'in anger' for the first time last night, although I'm typing the target name into SharpCap rather than using Stellarium to push the scope. I've downloaded the Imm stuff to add to my collection of catalogs, but as far as I can tell O'Meara is just in book form? Geoff

Hi Richard I can tell you what I do - but my apologies if I'm telling you what you already know. I'm also not sure what gear you have. I've got the 200PDS Newtonian Reflector on an HEQ5Pro mount, with the ASI585MC. Mount leveling - I don't worry too much about this, as long at the tiny spirit level on the mount looks roughly level. Collimation - I've spent a LOT of time on collimation and since I started with EAA at the end of January I've made gradual tweaks - but when you do collimate, be gentle, don't make big adjustments and try and understand what you're doing before making too many alterations - it's a slow gradual process. After last night I think I've got about as close as I'm going to get with my gear. I have a collimation cap that I'd used when I was just doing visual and managed to get fairly good results with that, but I've recently bought a StellaLyra Premium Cheshire from FLO, which I think has given me a bit more accuracy. @PeterC65 pointed me to this article on collimating Newtonians: Collimation Checks – Astro Diary (catshill.com). This is also good: Collimation - Newtonian Telescope - Reflector - Astro Baby's Guide to (astro-baby.com). I've also used the method described in this thread: Collimation of Newtonian Telescopes using SharpCap - SharpCap Forums - but you need an all sky lens. I've tweaked the focuser alignment to make sure it is perpendicular to the length of the tube, but I've tilted it slightly in the circumferential direction to get the secondary mirror centred in that direction. I've then done three or four iterations of collimating the secondary then the primary. Polar Align - I use SharpCap's built in polar align tool and can always get the polar align error down to less than 1 minute of error even with the fairly small field of view that I get with the 585MC (more often than not it's Good, sometimes it's Excellent) - I've got used to tweaking the alt and az bolts by very small amounts. I'm not sure what mount you have, but I think that an equatorial like mine will give a better result than an alt/az or dob. If you aren't using an EQ mount, then I think that shorter exposures (assuming you're aligning frames when live stacking with SharpCap) are better - maybe no more than 4s or 8s. Focus - I use a Bahtinov mask with SharpCap's focus tool - I got the mask for about £12 from someone on eBay who 3D prints them and, again, I always take time to get the best focus I can before locking the focuser with the thumb screw - and this usually lasts me for the night. I have a dual speed Crayford focuser that came with the scope, so can make very small tweaks and as it comes into the best focus I usually overshoot slightly then bring it back. Wind direction - I'm fortunate that I can almost always put the scope on the downwind side of the house, so that tends to dictate which bit of the sky I'm going to look at on a particular night. Frame Filtering - I normally use SharpCap's brightness frame filtering set to auto, which will eliminate poorer quality frames. Darks and Flats - I always do these, a flat when I'm setting up the scope in daylight, and a dark at the start of the session. I usually end up using the same gain and exposure all night, so generally just need one set of darks. Although these won't affect sharpness, I found that the darks really made a difference to the background noise but I'm still undecided about flats. Experience - when I look back to my first attempts in January, and what I got last night, I can see that I've improved over time. Here's M52 from 29 January, followed by M53 from 9 April. Hope this is helpful. Geoff

Thanks - and I think that the coma from previous images has gone/reduced since the collimation improvements, though I could do with a few more images to confirm this.

Sounds rather like last night for me too. I'd noted the '500 Best' when I was doing visual, before I started doing EAA, so I must add it to my EAA target list. Geoff

It had been two weeks since the last clear night and a promising forecast suggested a good night ahead. I’d spent a lot of time looking at my collimation since the last session and had bought a StellaLyra collimator (having previously used a collimation cap). After a minor tweak to the secondary mirror’s tilt, everything was lined up. I captured a flat, with dark correction, with the bottom of the OTA protected by a black shower cap that I’d recently bought to reduce light leakage around the primary. There was a brisk Westerly, so I set up on the lee side of the house, which gave me a good view of the Eastern sky. This is an unusual location for me, as the clear nights tend to come with a Northerly or Easterly wind. A long wait then until darkness came and I started SharpCap polar alignment. I tried a new procedure this time, starting the scope at 3h RA left of home, rather than the home position. This was when the night’s frustrations began. A glance up showed a line of black cloud coming in fast on the wind, with telltale streaks of rain. What do I do? It looked like it might just pass me by, so I quickly park the scope, switch off the mains power, grab a big bin liner and cover everything up. The wind was rising, so I stood out there holding the bin liner down, feeling the odd drop of rain on my head. Fortunately, the sky was clear behind the cloud and the wind soon moved it away. Switch everything on again, and polar align went the quickest I’ve seen it, so the offset start position is definitely worth trying again. Goto first target, then run SharpCap’s Brain – as usual it came up with gain 300 exposure 4s, so I quickly captured a dark, but looked again at the histogram and decided to go for 8s. Time was pressing, so I used a previous dark at a similar camera temperature. I have a big list of targets, but I’d built an observing list in Stellarium from the Cloudy Nights April EAA Challenge, so decided to go for these. The first was M53, and I’m delighted with the clarity and detail on this one, although only 96s total exposure. This was when the frustrations of the night continued, with a lump of black cloud blocking the view and Sharpcap continually dropping frames that weren’t bright enough, so I moved on. The rest of the night was spent chasing holes in the cloud – I’d goto a target, then the plate solve would fail because it was cloud blocked. After two more targets, M87 (5min) and M65 (3min), I gave up. There’s evidence of hot pixels on all the images, despite using dark correction. I’m wondering if these pixels have popped since I took the dark frame (it was from a few weeks ago). Geoff

I like detail of the tail in the latest picture.

Thank you everyone for the various pieces of advice - I suspect it is most likely moonlight. Although I’d read the SharpCap manual pretty much cover to cover while waiting for my camera to arrive, I hadn’t twigged about the background correction, so I think that the gradient removal will be worth a try while live stacking. And pick appropriate targets on moonlit nights. Geoff