PeterC65

Inspired by this thread I've decided to make some further enhancements to my 200PDS and 150PDS over the summer while they are not being used.

The biggest issue I have is dew build up on the secondary mirror. My EAA sessions tend to be quite long and after a couple of hours I start to see lots of noise in the background sky due to dew on the secondary. I've solved the problem of dew on the primary by using a dew heater band at that end of the scope, but even with a dew shield I still get dew on the secondary. So my plan is to install Backyard Universe secondary mirror covers and to fit fans to the primary to blow some of the warmed air up the tube towards the secondary. I've bought Noctua Redux fans and some cut to size plastic discs to which I will fit them. The plan is to use phono cables to supply power to the fans from the same supply that I use for the dew heaters.

I also find that I need to adjust the collimation of the secondary on the 200PDS most times I use it so I'm replacing the spiders with CNC versions (from CYCK), changing the adjustment screws to cap head hex bolts with a dedicated T-handle Allen key, and adding a washer between the adjustment bolts and the secondary stork. I've decided not to go with Bob's Knobs as I've read reports that they are too small to allow for accurate adjustment and to get the required torque.

I have also considered adding primary mirror masks but I don't currently have an issue with star shapes so I'm not going to do that at the moment.

It's also on the FLO website (here).

There is also an Altair version and a QHY version, both with the guide camera format. The Altair version is cheaper (£299 vs £349) and I believe it uses a super low noise mode of the IMX678 sensor (read noise is 0.42e to 2.43e vs 0.6e-3.5e).

I've been thinking about getting one of these camera for EAA. I have a OSC IMX585 camera at present and was thinking that monochrome might be better for faint objects. With 2x2 binning the IMX678 gives HD resolution and 4µm pixels which without the Bayer matrix is 571% better light grab (per pixel) than the IMX585 (in 1x1 binning mode).

Planetary Nebulae are worth the effort of finding as they look very impressive with a big Newtonian. Here's one of my favourites, the Eskimo Nebula (NGC2392), observed in early March with an 8" Newtonian with x1.7 Barlow, x400 gain (50%), 77 x 15s frames.

Ah, OK, that will limit you to short exposures. I find that for a given total exposure I can see more detail the longer I make the individual frame exposures.

I'd expect the background noise to reduce significantly as you reduce the gain. My camera's maximum gain is 800 and that's unusable, but it gets much better by 600, OK by 500 and optimal at 400.

The hot pixel removal feature in SharpCap is almost as good as taking darks, and a lot less hassle. I wouldn't both with darks or flats for now. I've only recently started using them, and then only sometimes. They seem to be most useful when pushing the optics at higher magnifications.

That's great for a first attempt. I'd suggest lowering the gain and increasing the exposure time. I operate my IMX585 based camera at half the maximum gain (decided after doing test shots at different gain settings) and I use between 4s and 15s exposures. The 10" aperture probably accounts for why you have such good images.

Prompted by this question I've taken a look at iTelescope and they do have some nice looking kit in some interesting places. These setups seem to be aimed at AP though. I can see how that might work, paying for data captured by a 20" so that you could enjoy the post processing part. I'm not sure that it would work for EAA though.

I like the idea of sharing with a buddy in the south though. I suppose the simplest was to do that would be via a live video broadcast which some do already.

I've only looked at the FLO offering and thought that was prohibitively expensive. Have you come across lower cost options?

In my quest for interesting objects to observe I often come across southern hemisphere objects that I will never be able to see from the UK (the Vela SNR being the most recent example). A suitably located remote telescope would be nice for these.

I'll give you process  try with my mount next time. It hadn't occurred to me to check the drift of stars within a frame to check what the maximum exposure time should be. Something I relly ought to do give I operate in AZ mode.

1 hour ago, LondonNeil said:

What's the zeo asi 120mc like?  There's one on astrobuysell for £80, which feels like a decent amount to spend to try something out.   

Or there's an svbony for £80 new

I've not used ZWO cameras myself but they have a very good reputation. The ASI120MC is their most basic camera but it is not dissimilar to my first astro camera which was good enough to persuade me that EAA was worth a punt. I would stick with a well regarded brand and get a colour camera as the images are more appealing. You could sell on the used ASI120MC for the same money.

You can observe DSO's via EAA but to do so you will usually have to stack multiple frames using software such as SharpCap. If you just plan to do live video then that will be limited to the Moon and brighter planets, and maybe things like M42. Bear in mind that with live video you get the same sort of atmospheric wobble that you see through an eyepiece.

Yes you're on the brink of the EAA rabbit hole, but the good news is that it isn't quite as deep as the AP rabbit hole.

I'd also recommend getting an astro camera and just connecting it via a USB cable to a laptop running SharpCap. Used astro cameras come up for sale very regularly if you just want to test the water. That's what I did then sold my first (used) camera on to buy something better new.

There are lots of additional things you can do once you have a camera (mount control, plate solving, camera calibration) but these are not needed just to be able to show on a screen what you can see with an eyepiece (you'll actually see much more and then maybe fall down the rabbit hole).

I don't do guiding for EAA. I have wondered about it but the consensus in the CN EAA Forum seems to be that it isn't worth it for EAA and as you mention, it would require more kit and more software.

I have experimented briefly with dither only guiding in SharpCap as I've read reports that it is useful, but it didn't make any difference for me and it was hard to get it to work. I usually use two scopes / cameras when I do EAA and SharpCap works by discarding frames when dithering which it can't do for the secondary camera so it may not be a good idea for me.

I operate the mount in AZ mode and as I understand it PEC is for EQ mode. I have considered trying EQ mode but that would limit me to one scope / camera and it feels like a lot of effort.

My EAA exposures are never more than 15s and so I think the only benefit I would get from any of these things would be smaller black edges as frames stack.

That's the scope I would be using. Interesting that you use a reducer with it. I had a cheap and cheerful x0.5 reducer for a while (this one) but it badly distorted the stars in the outer 50% of the FoV. I used it with my 72mm refractor for widefield as I didn't have the Newtonians at the time. What reducer do you have? Can you reach focus OK using it with the 8" Newtonian?

I've also missed 12P as it's below my local horizon when it's dark, but C/2023 A3 is well positioned for me so I have made a note to give it a try. What kit where you using to get this image?

I also observed the Whale Galaxy for the first time the other night and thought it was very impressive. I wasn't aware of the Siamese Twins but it's now on my list to try.

I've also made a note to give this a go. M87 isn't a galaxy I've observed so far as I just assumed it would be another fuzzy blob!

I've enjoyed watching the change in the NGC4216 supernova. Your post has inspired me to find others to follow.

I don't do even EAA between the middle of May and the end of July when it's not astronomically dark, but in August I concentrate on widefield as the Milky Way is more above the horizon for me. I already have the FMA135 which gives me 4.7° and this year I've bought an old Pentax 55mm M42 lens that will give me 11.6°.

I'd be very wary about leaving the kit outside unattended, but I have used SharpCap to play back live EAA sessions (for a demo to my local astro club) and that works well. If you set the playback frame rate to match the exposure time then the experience is identical to live.

2 hours ago, Fir Chlis said:

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?

The O'Meara objects are included in the Imm spreadsheet. I just filtered for them then copied that list into another spreadsheet that I've built to convert lists of objects into the JSON code needed to build a Stellarium Observing List.

I managed to fit in an EAA session last night between all the rain. Highlighting the Caldwell Objects in Stellarium, I could see that many of the smaller ones would be in view so I setup the Explorer 200PDS, Barlowed to maximise its magnification, and paired it with the 72mm refractor for some nice widefield context.

Observing lots of small galaxies can be a bit tedious but these Caldwell galaxies were an interesting mix, plus I observed the Eskimo Nebula (a PN) and revisited the supernova in NGC4216 which is clearly dimming now …

Probably the best of the night was NGC4565, the Needle Galaxy. Too big for the Explorer 200PDS really, but conveniently right across the diagonal so that it just fitted in the field of view.

The full report is here.

I managed an EAA session last night in between all the rain.

The rain has given me time to upload several object catalogs to Stellarium as Observation Lists. I could search these catalogs on Stellarium, but what I like about the Observing Lists is that I can highlight all the objects listed on the sky map and see which ones are above my local horizon. During an EAA session I can then just click on the highlighted objects and GOTO them.

Last night I highlighted the Caldwell Catalog, Imm’s Orphaned Beauties, and O’Meara’s Hidden Treasures. I’ve only recently become aware of all but the first of these, having downloaded the excellent spreadsheet and companion eBook produced by Gary Imm (see here). The spreadsheet lists thousands of interesting objects from many catalogs and allows these objects to be filtered and sorted. It is a tour de force in spreadsheet building! The eBook shows thumbnails of the more interesting objects from each catalog. Both are well worth downloading.

The Caldwell Catalog was indicating several objects would be visible to me, enough to keep me occupied all evening. All the objects were small so I setup the Explorer 200PDS with the x1.7 Barlow which gives me the highest magnification and smallest field of view of all my kit, and accompanied it with the 72mm refractor which gives a nice widefield view for context.

It being galaxy season, I spent the session looking at … galaxies, oh, and one PN.

I started with M44 as it’s bright and a good object to check that things are working, then on to the non-galaxy, NGC2392 (Eskimo Nebula). This really needs the magnification of the Barlowed 200PDS, and interestingly, it looked better with the UV / IR cut filter than with the L-eNhance.

After that came a string of galaxies …

NGC2775 – I could only make out a blob, no structure and an annoying satellite passing by.

NGC3115 – the Spindle Galaxy, but not M102, bright centre and edge on, still no structure visible …

NGC3626 – another blob with no structure, this time thankfully without the satellite trail, and with a smaller companion.

NGC4216 – a nice looking galaxy made more interesting recently by a supernova discovered in January. I’ve been keeping an eye on it every month, watching the supernova fade. Here is the progress so far …

NGC4449 – The Box Galaxy, it looks more like a nebula, with structure but not like you’d expect from a galaxy …

NGC4244 – the Silver Needle Galaxy, now I was seeing some structure, but the secondary was dewing up, despite the new dew shield …

NGC5005 – a spiral galaxy showing some structure, despite the dew.

NGC4631 – the Whale Galaxy, lots of structure and a definite whale shape, it looked better with the (dew free) 72mm refractor …

NGC4559 – the Koi Fish Galaxy, another spiral galaxy showing detail that I need to revisit when the secondary is free from dew.

NGC4889 – Coma B, not a very impressive galaxy in itself, but there are masses more nearby, enough to fill the field of view of even the 72mm refractor …

NGC4565 – the Needle Galaxy, too big to fit into the field of view of the Barlowed 200PDS normally, but conveniently on the diagonal last night, and probably the most impressive sight of the evening …

NGC4169 – The Box, this time not a single galaxy but four, arranged in a box …

NGC4395 –  the dew was really getting in the way which is a pity as this face on spiral galaxy showed some promise. Another one to revisit.

Lots of galaxies, but lots of variety, and almost all of them were new to me.

1 minute ago, Flame Nebula said:

The other point, and please forgive my ignorance, is that I'm planning to get the asiair plus, which I believe does plate solving, so maybe having star sense would not be needed for that, in this case?

I've not used the ASIair but I believe that it does plate solve and can control the mount. When I was looking at the StarSense for visual it crossed my mind that an alternative might be a finderscope, ASI120MM camera, and ASIair.

For me EAA means being sat inside in the warm with no need of an eyepiece. I wouldn't want to be nipping in and out, looking at the screen then looking through an eyepiece.

When I started EAA I used an eyepiece to align the scope once, but quickly realised that using the camera is better and easier.

The StarSense for Sky-Watcher has crossed my radar too. I see it as a way to do plate solving mount alignment for visual observing. One of the great advantages of EAA is plate solving, but I think £400 is a lot of money to make visual alignment that bit easier. If I align the mount well I can generally get the selected object into the field of view of a longer FL eyepiece with GOTO, but sometimes when there are no obvious pointers near a hard to see object (M33 comes to mind) it would be nice to have the assurance that the scope was at least pointing at the object. If I did a lot more visual and could afford Tele Vue and Takahashi then maybe ...

54 minutes ago, Fir Chlis said:

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. 

I can't see any coma in the images above.

It may have been a frustrating session but you got some very nice images.