Cosmic Geoff

I have a C8 SE, and with the stock 25mm Plossl eyepiece supplied the FOV is about half a degree, allowing the whole Moon to be visible. The FOV also depends on the eyepiece design - some offer more FOV for a given focal length than others. If you view with glasses this can also cut the field visible (I always remove my glasses to look theough an eyepiece).

Some more results from these planets, imaged with CPC800, ASI224MC, ADC, captured with Sharpcap 4. Mostly processed from 5000 frames of video. The visible region images of Mars were just an orange blur, but the IR images, shown here in original size and x2, show some detail despite the small angular size (7.5"). I need to find a Mars ephemeris and map to check what the Mars images appear to show. The Jupiter and Saturn images show less detail than I have captured at previous apparitions. The seeing did not look great. Saturn shown in visible & IR.

I suggest you take a hard look at what you want to achieve. Refractors are the traditional scope design, but there are other scope designs that get the job done and are much more cost-effective in the larger sizes. Dobsonian mounted reflectors give you the most aperture for your buck, but the simple mount restricts what you can do with them. You express an interest in imaging - well there are different styles of imaging: planetary, deep space, and EVAA - the latter combines the features of visual observing and imaging. There is widefield imaging - capturing the Milky Way and huge nebulae - and narrowfield imaging - planets and planetary nebulae and small distant galaxies. One set of kit will not do them all. And the kit is often expensive. And high demands are made of the mount. You only need a large scope nowadays if you want high resolution e.g. for planets, etc. For anything else, if you are not wedded to looking through eyepieces, a small refractor, a sensitive camera and some exposure time can do the job.

I have the EQ-5 mount which uses the same software. You will probably find that you don't get the uniform all-sky GoTO performance which an alt-azimuth GoTo mount usually delivers. Use two alignment stars in the East and look for objects in the East - should give good results. Use two alignment stars in the East and look for objects in the West - be prepared for major inaccuracy.

Why a refractor? A SCT with f6.3 focal reducer could give you a much larger aperture and focal length with a €3500 budget.

Quite. You need to find out which piece of software is causing the problem. I looked through the APT online help and there is a lot about cameras and no mention of e.g. a two-star GoTo align. So if your GoTo is going wrong, you should be checking that your GoTo app is performing properly, and if it is, then you need to look at APT or the integration of APT with the GoTo app.

I had a go at imaging Comet C/2017 K2 PANSTARRS on the night of 5 July. EVAA mode with 102mm f5 achro, ASI224MC, EQ5 Synscan. Post-processed with GIMP. Poor sky conditions.

I had considerable trouble trying to obtain a verified image of NGC6776. Taking the image wasn't the problem, but confirming the object was. Virtualcolony.com and several other online sources quote it as being the same object as NGC 6884 (in Cygnus) while my Synscan and Cartes du Ciel indicate that it's a separate object in Lyra.

The FITS stack is now working properly, and I think I have figured out the answer to this. If you set 'Debayer Preview' to ON, all is well, similarly if you set it to RGGB (with an ASI224MC). But if you set the 'Debayer Preview' to an incorrect setting like GRBG, it looks wrong on the preview and this wrong colour balance persists in the saved stacked FITS image.

Somwehere on this forum I recently saw a link to a company that supplies replacement corrector lenses for these SCTs. If you do as you suggest the assembly will suffer from the aberrations the corrector plate is supposed to correct.

Having looked up the specs, I see what you mean. Despite the eye-watering price, the mount does not come with a smart handset of the kind provided by Celestron or Sky-watcher. So I'll modify my question to: can the GoTo functions be performed successfully via your tablet or laptop if you don't involve APT etc (which are not needed to make a Celestron or Sky-watcher mount work)? BTW, to successfully restart from PARK with a Sky-watcher mount, one has to perform the following: mechanical polar align, star align, select PARK, & Park to Home Position in utilities (mount moves to home position, announces parameters saved, requests power off.) On power on, it requests: Start from PARK yes/no? I expect that your mount will have to do the same (though not with the same software or technical terms.) I installed APT on a laptop but have not done more than set it up as I found that Sharpcap 4 performed all the functions I really wanted. A lot of people are confused by the Sky-watcher alignment system, which assumes a Home position pointing at the NCP and will slew to the general direction of sundry objects (algnment stars) before a star alignment is performed, using only the home position and the time/date.

I found that virtualcolony.com/sac/ has useful lists of planetary nebulae down to very faint ones. I printed off lists for Aquila and Cygnus down to mag. 15, lists that contain a number of planetaries not in the "!00 Brightest" list. On June 25 2022 I had a go at some with NGC catalog numbers (easier to enter into Synscan). Gear: 102mm f5 achro, ASI224MC, EQ5 Synscan, captured with Sharpcap. I targeted IC4846, NGC6766, NGC6772, NGC6778, NGC6785, NGC6807, NGC6833, NGC6881, NGC6894 and NGC7026 and identified almost all of them. I had a problem with the colour of the stacked images. I was puzzled by NGC6766 which seems to be the same position, brightness and size as NGC6884 which I recorded last year - an easy blue object. Three sample images are shown below.

Some people may not enjoy using just one eye, but the only way to know if you will get on with this or not is to obtain (or borrow) a starter telescope and try it. For beginners on a budget, neither electronically assisted astronomy (which requires a substantial outlay) nor binoviewers (which have a significant cost, and not all telescopes work with them) are an option. Binoviewers potentially give an enhanced view, but are more difficult to use than a single eyepiece. Making the two images merge can be tricky. Binoculars are a reasonable option for a beginner but restricted to low magnification.

JayMS - can you confirm that the mount works properly when operated according to the user manual without the computer connection and with the handset? If it doesn't there is no point in trying to use APT etc. I am not sure what you mean by sync. You might find it useful to explain that in more detail. Moving the mount manually rather than via the GoTo handset is usually a no-no. It should be easy enough to centre the star with the hand controller if you can see it on screen - just press the direction buttons till you hit the ones that move it in the right direction. That may sound dumb but it's just how it is. (With an alt-azimuth mount one can predict what the buttons are going to do.) Again, I am not familiar with your mount, but most GoTo mounts work in a similar manner, and some may use essentially the same software as more popular brands.

Depends what kind of astrophotography you have in mind. Some people use Schmidt-cassegrains for imaging small galaxies and the like. Also great for planets. (Smaller aperture refractors are considered more user-friendly than a big SCT for astrophotography.) Some might think that an 11" SCT is under-mounted on an AVX. I suggest seeking further advice. Keeping a stellar image inside a 2' (two minutes of arc?) for 10 seconds does not seem an exacting requirement for a GoTo mount. I think my GoTo mounts perform much better than that.

I suggest you hold fire on all that for a while. The EQ6 is a popular imaging mount but by all accounts a C9.25 is not the ideal scope for a beginner in deep space astrophotography. Something like the 80mm refractors often recommended would be far easier to use. You don't need a large aperture - I have imaged mag. 14 objects with a 102mm refractor, even got Pluto with an alt-azimuth GoTo mount. I suggest you see how long an exposure you can run with your existing setup without getting star trails - you may be pleasantly surprised. 🙂

I am not familiar with your mount, but I do not see any indication above that you performed a goto alignment at any time. Typically this entails entering the date and time and geographical position, and fine-aiming the telescope at one, two, or three bright alignment stars. A mechanical polar alignment is only part of the process. This full process has to be mastered before using software like ATP and Stellarium.

I got up early on 2nd July to have a go at imaging Jupiter, Mars and Saturn in visible and infrared. I forgot to use the ADC and the images of Jupiter and Saturn were a little disappointing. CPC800, ASI224MC, captured with Sharpcap 4. At least got to practice my methods. The Mars images however exceeded my low expectations, and show some surface detail. Two are visible light, two IR.

I have done EVAA with a CPC800 (8" SCT fork mounted, alt-azimuth GoTo), Celestron f6.3 focal reducer, ASI224MC camera, Celestron standard diagonal, Celestron dew shield. Software: Sharpcap 4 on Windows 10 on Dell Vostro. That's it: I don't think I need any other bits & bobs. It works quite well on small targets like planetary nebulae. Good luck and clear skies! I have the setup to do platesolve & resync but this technique works better with a wider FOV. Note that if you are using a fork mounted scope like the C9.25 Evo you will need to use a diagonal, both to get the correct spacing for the focal reducer and to prevent the large camera hitting the base of the mount.

Assuming you intend to put it on an equatorial mount, read up on 'cone error'.

I had a further look into this and am more confused than ever. I was wrong about that setting in Sharpcap 4 : Debayering FITS with PIPP Not Working in Version 4 - SharpCap Forums It looks like I was not using 32-bit files so this is not relevant. I was also wrong about the camera not being relevant - I tried some shots with my ASI120MC camera of the same targets as with the ASI224MC. With the ASI120MC the .png single shot and the .fits stack come out having the same colour rendering (and the bright stars don't have green haloes). With the ASI224MC the results are as above. I also noted that when processing a FITS file in PIPP, it does not matter what debayering options are selected, the result is exactly the same. Maybe the stacked FITS file is already debayered? Also noted that when processing a .png file from either camera, it is possible to recreate the 'green halo' effect by selecting a 'wrong' debayering option. Still baffled.

I upgraded mine and I do not think there is any difference at all. Doing the upgrade is simply a matter of unbolting the unwanted parts and bolting on the kit parts.

While doing some EVAA imaging of faint planetary nebulae I became aware of a problem with live stacked images stored as FITS files. Kit: 102mm f5 achro, ASI224MC camera, EQ5 Synscan mount, Sharpcap4. I noticed that the colours in some of the de-bayered FITS images, converted to TIFF in the de-bayering using PIPP, looked off. I nearly always take a companion single shot saved as a .png image. I will try to give examples below. You will note that the de-bayered .png image has credible colours for various stars and for the nebula in the centre, which looks blue-green. The live-stacked FITS image, hovever, debayered and converted to .tiff in PIPP, exported as a jpg in GIMP, has green stars! -which is plainly wrong. They also look green in the PIPP preview, BTW. This is the most extreme example I have found so far - mostly the FITS colours just look less saturated or a bit off. (Note that I am not concerned about those blue or green fringed stars as such - they appear because I have not invested in an ED or APO scope.) So what's wrong? Clearly not the camera. After some digging, I found that Sharpcap 4, unlike the previous version, has settings in the Image tab where one can set the indication of the Bayer matrix to be correct for PIPP (etc) or Astap (etc) and unlike the previous version it defaults to the latter. OK, fine, so I just have to change that setting to PIPP (etc), reprocess the previous images (since I installed Sharpcap4) and the problem is solved? Actually, no...☹️. I tried loading the NGC7026 FITS into ASTAP and found I could have either green stars (which it seemed to default to) or a perfectly monochrome image. Nothing else. That leaves two other programs (mentioned in the Sharpcap settings. Pixinsight is a paid-for program, and My Windows 10 wanted nothing to do with opening Siril. At which point I gave up. Any ideas? Stack_16bits_10frames_100s.tif

If you search in the EAA Reports you should find some images I made with the 102mm achro.

I use for EAA both a 102mm achro refractor on an EQ-5 Synscan with an ASI224MC camera, and also a CPC800 with a f6.3 focal reducer and the ASI224MC camera. If I had to pick just one I'd use the 102mm setup. The CPC800 setup (which gives much the same FOV you'd get with an 8" Newtonian) is more suited to small objects like planetary nebulae. I basically used kit I already had on hand (except for buying the focal reducer. ) Your choice is whether to aim for a widefield or narrowfield setup, and how much you want to spend on a camera. The ASI224MC is a planetary camera but works just fine for deep space except that the chip is small, hence narrow FOV. I also strongly recommend that you aim for a full GoTo, which will let you easily find faint targets and use platesolve & resync to confirm you are aiming at the right place. An equatorial mount is not necessary for the short exposures you are likely to be using, but the choice of alt-az GoTo mounts is limited, and the equatorial gives you the option of trying long exposures.