Skip to main content

Remote Imaging with a Lisa?

5 posts / 0 new
Last post
Ed Wiley_WEY
Ed Wiley_WEY's picture
Remote Imaging with a Lisa?

I had a Shelyak APLY 600 and did some spectroscopy with it a couple of years ago using ISIS for data reduction. However, I sold it when I moved and established my remote observatory, switching back to doing only photometry.  I have been looking at the LISA with its calibration module and photometry slit and wondering how feasible it would be to use this instrument remotely and whether anyone is using the photometric slit to do photometry as well as spectroscopy. I would hate to give up photometry, Christian Buil's write up on combining both spectroscopy and photometry looks interesting if a bit process heavy.  If you are using the Lisa (or LHiresIII for that matter) remotely I would love to hear your experiences.

Background: AP900, C11 Edge (F7/F10), Moravian G2 1600 NABG, Lodestar X2 OAG; SGP/ASCOM, Win10, remotely controlled via Remote Desktop (RDP). Observatory is two hours away.

Thanks, Ed

Ed Wiley_WEY
Ed Wiley_WEY's picture
Question answered

Olivier Garde of Shelyak was kind enough to answer the question. The problem with true remote imaging is temperture change. The inner lens doublet may change focus with changing temperatures and this cannot be adjusted remotely. Since we have large temperature changes at our Texas Hill Country observatory I have concluded that remote imaging with the Lisa is not for me.

Ed

Robin Leadbeater
ALPY 600 ?

Hi Ed,

I would forget the LHIRES for remote operation. It is very difficult to operate remotely reliably and has worse stability than the LISA

The ALPYmight be a better bet. I dont have the fast large swings in temperature you have but mine seems pretty stable even from winter to summer. Did you find that when you had the ALPY ?  It it is easy to operate remotely ( I do this routinely without needing to intervene physically, if only over a few dozen yards over wifi)

Getting  photometry from spectra is tough though (Not so much the data reduction side but getting a good spectrophotometric, absolute calibrated spectrum)  Unlike differential photometry, you cannot measure both target and reference simultaneously with a slit spectrograph. This means you need photometric quality skies (or at least spatially and temporaly stable atmospheric conditions long enough to take both target and reference spectra). Also unlike photometric comparison stars, good spectroscopic standards are few and far between.

Alternative approaches could be 

1. Add a seperate scope dedicated to photometry on the same mount

2.  Select the photometry filter wheel plus camera or the spectrograph via a motorised flip mirror 

3.  Do photometry on the guider image (I know someone doing this with the ALPY though the size of the field with sharp enough stars might limit the choice of comparison stars

Robin

Eric Dose
Eric Dose's picture
Dear spectrograph designers,

Mostly addressed to astro-spectrograph designers/vendors:

(1) When someone makes a high/medium-res spectrograph capable of remote operation out of the box, spectroscopy will get the broader interest from advanced photometrists that we all want it to have. Unlikely before. Yes, we're watching.

(2) It's the most photometric skies that cause the widest temperature ranges. And changing fastest in early evenings when people most want to observe, remotely or not.  Bad luck, but there it is. So you'll simply need to design for that, I suspect.

Ed Wiley_WEY
Ed Wiley_WEY's picture
Alpy 600

Hi Robin and Eric:

Thanks to both of you for your comments. Eric, I agree about design.

Robin: Like you, I found the Aply 600 pretty stable and very useable in its full configuration. The problem for my interests is resolution. The Aply simply did not have the resolution I wanted for the targets I am interested in studying. So when I went remote I sold the Aply to a university who could use it for student projects. I note that the AAVSO Spectroscopy programs are mostly for instruments with a minimum resolution of R=1000, so when I thought to acquire another instrument, the Lisa was the minimum-resolution spectrograph I considered. 

I greatly appreciated Olivier's comments and evaluation, I have always found the Shelyak folks to be honest and helpful about their products.

Ed

Log in to post comments
AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484