Affiliation
American Association of Variable Star Observers (AAVSO)
Fri, 06/24/2022 - 22:34

Hi,

I'm a relatively new member of AAVSO, and interested in citizen science.  I have a question about equipment, specifically telescopes.

I currently have a 14" Celestron SCT on a German Equatorial mount.  I'm considering replacing the SCT with something smaller, but I'm curious about what is going to be best for citizen science or at least get some thoughts on that.  I'm considering downsizing to something like a 4" quality refractor, but I'm in no rush and could just as easily keep my SCT. (it's just that I'm 71, and dealing with the bulk of that thing could get to be a little onerous).

Are there any guidelines that might be useful here? I get that the 14" can reach "deeper", but is that amount of aperture unnecessary for most citizen science or is it really helpful? For studying variable stars vs exoplanets? I suppose that that question could go beyond AAVSO work.  

Thanks.

Ron

Affiliation
American Association of Variable Star Observers (AAVSO)
Ron,

It would be helpful if…

Ron,

It would be helpful if you could provide more information. Are you competent working with the mount, ota and the focal length you have described? Can you accurately point and guide for astrophotography? What exposures are you reliably using for your subs? Are your ota considerations due to your needing to set up your equipment nightly, or do you have a protected semi-permanent location for your equipment? 

I am only a couple of years into photometry and there will certainly be others with more experience that can advise you. But I have more recently faced similar questions to yours. It seems to me that if you are comfortable and competent with your current equipment (including plate solving) then it would be good for photometry. Perhaps working at a shorter f/l by using a focal reducer. I am currently working at 1645mm with a 9.25" f/10 SCT mounted in my roll off roof observatory and I have more photometric opportunities than I have time for. I do have an excellent CCD camera that allows me to collect data down to 16m without exposure times being too long (<120").

Most importantly I recommend you apply for and engage a mentor to help you along the way. THAT was the most important and beneficial action I took at the beginning. 

John  

 

Ron,

 

Lots of good…

Ron,

 

Lots of good questions! All very personal in nature.

I too have a C-14, and it is OK for visual use but a little "bouncy" for imaging. My plan is to sell it and replace with a C-11, devoting the extra $$ into imaging equipment. But that's just me!

You can do very useful variable star work with a 4" refractor! I note that about half the AAVSONet instruments are Tak 180mm Epsilon reflectors. I use them and routinely get useful images to below 15mag. Of course they are f2.8!!

One avenue is to utilize AAVSONet instruments first. Get comfortable doing processing and reporting before you use your own instruments. What kinds of stars interest you?? Are there any in the 8-14 mag range??

Peter

 

 

 

Affiliation
American Association of Variable Star Observers (AAVSO)
AAVSONet instruments?

Hi Peter,

Thanks for your thoughts.  Much appreciated.

I wasn't sure exactly what you meant by "utilize AAVOSNet instruments first".  Can you add a bit of thought to that, please? 

I'm not sure exactly what kinds of stars interest me at this point.  It's more like I was looking for potential citizen science work to do with my telescope or something similar, came across AAVSO and their work with variable stars and exoplanets, and decided to check that out without knowing much more than that. 

I can actually run my telescope at f/2 by adding a piece of optics called a Hyperstar.  I haven't done much with it yet; there are people who love it, and people who want to love it, but have a hard time getting to "behave" the way that they want.  

It's interesting that you mention the 4" refractor because in a discussion I'm having separately, that's been suggested to me as an alternative telescope.  There are tradeoffs, of course, but it might be a possibility.  The question is what I'd lose by giving up that much aperture, while considering whether that 14" aperture is all that usable under my skies.  

 

Thanks again.

Ron

 

Ron,

While you're still…

Ron,

While you're still deciding on your citizen science interests, I mentioned using AAVSONet instruments. If you're an AAVSO member, and I think you are, you can propose observing variable stars on a worldwide network of telescope systems AAVSO members can access. Check out the AAVSONet section: https://www.aavso.org/bright-star-monitor-section

I have a short overview PPT or PDF I could send you if I get your email address. Its an early rev of a presentation I'm giving in late July.

One reason I suggested AAVSONet is that you are not required to know the "system stuff", calibrated images are provided to you. You also don't need to invest in moderately pricey filters until you are sure you want to dive in.

For a beginner, and I am one having only been observing variables for 3 years, pick stars that have significant variability over short time periods. Others are better suited to make suggestions, but think UXOR or T Tauri stars where dust clouds orbiting the star occult it periodically. Check out Young Stellar Objects and Eclipsing Binary sections: both have suggested stars.

Feel free to reach out to me at pbealo@comcast.net for private chats, if you wish.

Peter

BPEC

 

 

 

Affiliation
American Association of Variable Star Observers (AAVSO)
Thanks for that info, Peter…

Thanks for that info, Peter.  I took a quick look over at AAVSONet, and now I understand what you were referring to.

Yes, if it wouldn't be too much trouble, I'd love to see that PDF.  I'm at rgafron@comcast.net.

And thanks, I may drop you a separate note.  I've got a lot of ideas floating around, and lot of suggestions, and it might be helpful to just share that a bit.

Ron

Affiliation
American Association of Variable Star Observers (AAVSO)
High Bortle level

Ron:

You might want to comment on your sky conditions as part of the equipment discussion.

Tom

 

Affiliation
American Association of Variable Star Observers (AAVSO)
A few more thoughts about my sky conditions and more

Tom suggested that I might offer some additional information about my sky conditions where I use this telescope.

So, I live in the suburbs outside of Chicago, Illinois, USA.  As you might expect, our skies are not exactly "immaculate".  I think the maps put us at about Bortle 8.  We average about 2 clear nights a week, with a couple more partly cloudy nights.  Of course, it varies with time of year.  That's what I've got.

I've seen people do some remarkable astrophotography from locations just like mine, and worse, actually, so I'm thinking that worthwhile citizen science work can be done as well.  I could be deluding myself; it wouldn't be the first time. :-)

As far as my setup, some additional thoughts.  Last year, I had to break down the entire system to get some repairs and tuning to the mount and the OTA.  I'm in the process of getting everything added back in and "tuned" again.  When everything is really "happy", yes, I can do exposures several minutes long with no trailing running at f/10, although that is hard to achieve; I can get a couple of minutes without too much trouble.  The telescope runs natively at f/10, but I can also run at about f/6.8, I think, using a focal reducer.  There is also an additional piece of optics I can add to the telescope called a Hyperstar that allows it to run at f/2.  I'm assuming that once I have everything reassembled, I'll be able to get those kinds of exposures again.  It's a challenge.  Part of the challenge is kind of fun, but it can be pretty frustrating when a camera won't connect or slewing to a new target just doesn't feel like working that night.  

Someone asked about plate solving, and yes, I can do that.  The Celestron mount has an accessory called Skysense that uses an additional small camera to image the sky and then plate solve, several times, in order to help the mount figure out where it's pointing.  I haven't tried other tools for plate solving but I know that they exist. Currently, I'm working on getting the Skysense added back to the system and working reliably (Celestron has a history of using crappy cable connections that make life interesting). 

I've got a couple of other components to add that assist with alignment, and then I'll be adding my guidescope to the mix.  

 

Affiliation
American Association of Variable Star Observers (AAVSO)
My setup for astrospectroscopy

I too am pretty new to AAVSO, having been a member for just about two years.  My suggestion is to not buy anything just yet.  You first need to commit yourself to a mode of observing and then tailor any new items to that goal.  My own interest began with photometry, but then I learned about spectroscopy and that's where I am now.

I have a Celestron EdgeHD8 scope equipped with a spectrograph.  I have a Canon DSLR piggy back on the Edge8 and I use that for photometry of the star targeted for its spectra.  The 8" scope with reducer is F/7 instead of the native F/10.  I found that the field of view (FOV) with the 8" scope was just too small to be able to do photometry.  But, the Canon with its "kit" lens zoomed out to 300 mm gives a FOV of about 3 x 4 degrees, which is large enough to have plenty of stars for comparing to the target star.  Even though the Canon is not nearly as sensitive as a dedicated astro camera, it can still see very dim stars with just a short exposure. In fact, a more common problem is overexposing! Photometry purists are not satisfied with a DSLR for very precise work, but for me, it's just a supporting instrument. 

I too have the Celestron StarSense, and if someone wanted it, I would be happy to sell it.  I no longer use it.  When we talk about plate solving, that's not what you get from the StarSense camera.  You need to be able to capture an image and solve it in real time to be sure you are indeed centered on your target.  There are many astronomy software packages that do that in conjunction with controlling everything (I use the freeware "APT").  Your image for plate solving needs to come either from a guide camera or the main scope itself, and when the plate solve is successful, the software will sync your mount to the actual coordinates.  My system stays set up in my mini-observatory all the time, and at the end of each session, I tell it to hibernate; then I 'wake it up' the next time I observe, and so I do not have to orient it and create a new sky model saving lots of time and frustration.

Good luck figuring all this out as you get deeper involved.  Welcome to the club.

Rick

ps.  My mount and scope are heavy, and I could not continue in this activity if I had to set it up each time.  You did not mention which mount you are using, but your whole rig must weigh a couple hundred pounds!  As for spectroscopy, you need a lot of light, and my 8" scope is the minimum.  A 14" at F/10 would be great!

Affiliation
American Association of Variable Star Observers (AAVSO)
My setup right now is a lot…

My setup right now is a lot better than it was.  I do have the mount, a Celestron CGE, set up on a pier which I built out of 4 4x4 bolted together and sunk into about 4 feet of concrete.  It's fairly solid, although I'm sure that there are downsides to doing it this way.  But, I don't need to lug the really heavy stuff out there every day.  The telescope and the mount are inside of a Rubbermaid storage cabinet that I reinforced and modified with some rollers on the bottom.  Basically, I open up the cabinet and roll it away from the telescope when I go out.  It's a pretty tight fit, and so I still need to bring out everything else. Right now, I don't have permanent power to the pier, but that's something I'm working on this summer.  Sure, I'd love to having something like a NexDome, but this cost me about 600 bucks compared to 3 grand, at least, for a real dome.  I've got it set up on my deck (I wish I could add a couple of pictures, but I can't quite see how to do that here yet; strange because in the private forum for the AAVSO class I'm taking, we can attach files to our posts), with the post isolated from the rest of the deck.  Because I have to move the telescope as I put it into the cabinet, I usually have to disengage the clutches to make the moves easy, so I don't currently try to hibernate it.  

Right now, I feel like I've got a ton of options. I had to disassemble everything last year to have some work done on the mount and the OTA, so what I'm thinking right now is that as I add everything back to the telescope, I want to see just how good I can get it, and that might tell me if I should keep it or make a switch.  

Thanks for your thoughts.  I really do appreciate it.

Ron

Affiliation
American Association of Variable Star Observers (AAVSO)
Equipment for photometry?

Ron,

I think that in most cases the best scope for the photometry beginner is the one he/she has right now.  There are plenty of targets for 14 inch scopes (and for scopes of almost any size).

The most important piece of equipment is the mount.  If your mount works well with the 14 I would stick with what you have.

Regarding 14 inch SCT for a 71 y.o. body:  Do you have an observatory or telescope shed?  If not, do you have a spot where you could put up a simple roll-off shed?  Having your equipment already set up, aligned, and with all the wires connected is a major step to make your observing easier at any age.

It is important to pick a camera which is compatible with your scope (focal length).   With my 14 inch SCT I use a camera with 25 micron pixels, very hard to find now.  Nine micron pixels used with a focal reducer, maybe also with binning 2X2,  would work in most cases.  Many people make the mistake of buying a new camera with tiny pixels thinking that would give better resolution.  Not so.  The limiting factor for resolution for most of us is the atmosphere. 

Make sure you read and understand the section of the AAVSO CCD Photometry Guide that deals with image sampling before you buy a camera.  Look for a camera with a large chip and large pixels if you use the 14.  This probably means you'll be looking for a CCD camera rather than CMOS.  Most CMOS cameras have small pixels.  A non-antiblooming CCD camera would be preferable, but an anti-blooming camera will also do fine as well.

Phil