Automated observation for SN, comet or asteroid search
The main purpose of this telescope is to detect new SNs, Comets or asteroids. It's extremely painful to achieve this goal in an interactive way by clicking over buttons and panels over the whole night. Also the user is very prone to mistakes after a several hour of observations.Observing over night is always not compatible with normal working hours. A new reliable way to observe must be undertaken. In order to overcome these problems, we (Boris Gaillard and me) have programmed the PRiSM software so as to be able to observe automatically (it means : moving the telescope, take images in a given mode and store them into the hard disk).
I'm going now to describe how PRISM (beta v5.04) can achieve this kind of observations (SN search for instance). It worked out well with Maya CCD camera and MCMT drives/encoders, but it's made in a way to withstand with ANY CCD camera and telescope system implemented in PRiSM. We were able to make it run for the first time with our T250 telescope successfully. The telescope(= drives and encoders) and the CCD camera must be online to achieve this automatic observations. Concerns must be kept about the cables around the telescope...
This mode cannot yet be remotely controled over long distance internet connection (PPP connections for instance), BUT can be used with display exports from PC to another PC over a Local Area Network by using softwares such as VNC.
STEP #1 : Select objects from Sky Map
First of all, we have to select objects by using the "find around panel" and retrieve a list of galaxy according to criteria such as field to explore, Minimum object size, RA/DEC window and catalog type. From that, we get a list of galaxy, a click to "Ajouter List OBJL" (still in French sorry, means "add to OBJL list") allows to add those objects to the MAIN PRiSM observing list object panel.
STEP #2 : Import them to the main observing list
The PRISM main object list panel pops up, showing all the objects selected to observe, this panel gives the current observed status, the meridian angle, the distance from the telescope actual location. This panel can be used also to observe in a semi-automated mode (user can slew the telescope to a given object).
All the objects to be observed appear in blue into the sky map. The current telescope location is the yellow crossed circle.
STEP #3 : Create and build the observing block
The last step consists in building the observing script with the observation scheduler. You just need to set how those objects will be recorded (location in the sky, CCD camera modes, exposure time, binning, etc etc) and to import the object list from the MAIN object observing list. Once this step made, the script needs to be built by clicking the "Build script button" and it will generate automatically a very complicated PRiSM's PGM script text file in a single click !
The last step consists in building the observing script with the observation scheduler. You just need to set how those objects are to be recorded (location in the sky, CCD camera modes) and to import the object list from the main object observing list. The script needs now to be built by clicking the "Build script button" and it will make a complicated PGM PRiSM script text file in a single click ! Have a look here to see the automated generated script file.
STEP #4 : Observe !!
Now, the script file (PGM file) can be launched from the acquisition panel, the telescope will slew to objects, record them and save the files AUTOMATICALLY.
After a while (in the meanwhile you can either sleep, watch TV, wash the dishes (yes! it happens to me) during the observing phase), the observation script is over, and all CCD images with objects recorded are stored into the hard disk :
This is the observing LOG file :
Field in progress :NGC3359
Field done
Field in progress :NGC3556
Field done
Field in progress :NGC3587
Field done
Field in progress :NGC3610
.......
Field in progress :NGC4814
Field done
Field in progress :NGC5205
Field done
Observation is over
This shows an example, with 61 fields taken between 21h51 UT and 23h35 UT (i.e. during 1h44m). So, one object every 1min42sec (1min exposure+20sec readout time+20 sec pointing). It means that over a night of 8 hours 278 fields can be recorded. Here it covers 900 squares degrees, the whole sky is 41260 square degrees (i.e 2.2% of the whole sky).
Hereafter, raw images (60 sec exposure, binning 1x1), still observed thru my illuminated garden...
N4605
N3963
N3963, From BT-ATLAS
Now, all the images can be checked for SNs by comparing them with Atlases such as BT-ATLAS, Pises-Atlas or Digital Sky Survey.
To conclude this page, have a look to this animated gif file showing the telescope slewing to a target :
