B star survey

[Andrew Smith]

Just managed to acquire 35 B star spectra with magnitudes between 5.5 and 7.5 in under one hour! This was 35 out of the 36 B stars in the Hipparcos/Tycho catalog between RA 18 to 19hrs and Dec 20 to 40 deg. This is the first real run in my attempt to find new Be stars however, all were in absorption! I still need to investigate what happened to the 36th HIP92036 and fine tune the exposures to get a more balanced S/N across the magnitude range.

The conditions were not ideal with thin cloud and astronomical twilight not yet over!

The spectrograph was a LISA with a 100 micron slit and I used my 300mm Newtonian on a Paramount ME with a custom script running in The Sky X to center the stars on the slit and take the spectra.

Regards Andrew

[Robin Leadbeater]

Hi Andrew,

That is fantastic productivity ! Did it need any manual intervention after you set it running?

Cheers
Robin

[Andrew Smith]

Hi Robin, no intervention at all! After opening the roof and switching the power on I just run the script. The only task at the end is to switch off the power and close the roof. As I don't trust the weather I watch the spectra as they come in using Rspec.

The productivity will go down a tad as I will increase the exposure for mag 7 to 7.5 stars from 60 to 100s.

Regards Andrew

[Ken Harrison]

Great stuff!
Well done.
With a 100micron slit gap you're effectively working "slit-less" and lo res.
Would your system work with a 20micron gap? Plate solving?
Are you guiding for the 60s exposure, or just tracking?
It would be good to see your results....

[Olivier Thizy]

Andrew,


excellent !

Looks like automated observations in slit-based spectroscopy has been successful so far with AudeLA (Lhires III and eShel spectrographs), PRISM9 (LISA) and now the Sky X (LISA)...


Cordialement,
Olivier Thizy
Vous ne verrez plus des étoiles comme avant !
http://www.shelyak.com/en/

[Andrew Smith]

Hi Ken, Thanks for your comments.
I prefer to call my method of operation "Wide slit" i.e. where the spectral resolution is set my the seeing and guiding accuracy rather than slit-less as the sky background is reduced to the contribution from within the slit rather than the whole field. However, you are right it is low resolution.

The system uses the accurate pointing of the Paramount ME/The Sky X to get the target in the field then plate solves to get the exact co-ordinates at the center of the image. The script then centers the target and jogs it onto the slit. I don't guide but use the precision tracking (ProTrack) option. I have not tested this to the limits but multi-minute exposures should be ok. I did post an image of the system centering a star on a 15 micron slit, a while back, so 20 microns should be ok. I feel it is as accurate as I could do manually, if not better.

I don't guide but all the necessary objects are available for someone to script this. Indeed current commercial packages do this but with two exceptions. One they center the field using the main camera not the guide camera and two no option to offset the target onto a slit.

I attach 3 spectra as I would see them come in across the range of magnitude. Remember they are just to see if the star has any emission features and so the S/N is lowish (too low for the faintest object). The aim is to maximize the number of stars surveyed.

Regards Andrew

[Andrew Smith]

Andrew,


excellent !

Looks like automated observations in slit-based spectroscopy has been successful so far with AudeLA (Lhires III and eShel spectrographs), PRISM9 (LISA) and now the Sky X (LISA)...


Cordialement,
Olivier Thizy
Vous ne verrez plus des étoiles comme avant !
http://www.shelyak.com/en/

Hi Olivier, yes automation is fun. Just for my education did/does the AudeLA software allow for the automatic centering of the target on the fiber or slit as well as obtaining the spectra? I ask as this was by far the biggest challenge. As I could not mechanically center the LISA slit to image to the center of the field, to the required accuracy, I need to custom code jogging the target onto it. To make it doubly fun you have to allow for the slit flipping sides as my eq mount does its meridian dance.

Also, I must have missed your post on the PRISM9 (LISA) or was it your recent post on PRISM9(SA)?

I have also done automated collection using the SA both in a low res slit-less spectrograph and native. With no slit it is really just down to accurate pointing and tracking/guiding no programming required on my part!

Regards Andrew

[Francois Teyssier]

What a nice project !
Often proposed but never performed !
Keep us informed of your results,
All the best for this interesting subject

François

[Andrew Smith]

Hi Francois, the idea did of course come from reading your "Low Resolution Spectroscopy Observers Guide". If you have any further advice on how to perform the search I would be pleased to have it.

Regards Andrew