Virtual Observatory India

HCT Data Archive System

Introduction

Himalayan Chandra Telescope (HCT)

A 2-m aperture optical-infrared telescope, the Himalayan Chandra Telescope (HCT) manufactured by the EOS Technologies Inc., Tuscon, Arizona, USA is installed at IAO. The telescope is remotely operated from CREST, Hosakote, via a dedicated satellite link.
The telescope is equipped with 3 science instruments which are mounted on an instrument mount cube at the cassegrain focus of the telescope. The instrument mount cube has four side ports and an on-axis port, which makes all three instruments available mounted on the telescope. The instruments currently available are the Himalaya Faint Object Spectrograph (HFOSC), the near-IR imager, and the optical CCD imager. The HCT is hosted by the Indian Institute of Astrophysics (IIA), Bangalore. For more details on the HCT and IIA logon to http://www.iiap.res.in

HCT Data Archive System

The HCT Data Archive System (DAS) is a web-based system which is employed to archive observational data generated by HCT and provide a querying mechanism to access the archived data. DAS is designed keeping in mind the various users and their privileges in accessing the telescope data. It facilitates administrative functions such as making data public, registering users for data access etc. It also allows data downloads to principal investigators and registered users.
This system has been developed by Persistent Systems Ltd. (PSL) in collaboration with the Inter-University Centre for Astronomy and Astrophysics (IUCAA) and the Indian Institute of Astrophysics under the Virtual Observatory-India (VO-India) initiative.

System Details

This is a web-based system. It provides unique logins to registered users and principal investigators (PI). The data from telescope is in the form of images or spectra along with associated metadata. The metadata is parsed and archived into the backend database. The users can query this metadata.

The screenshot of the HCT DAS for query page is shown below.

The user can specify one or more than one query parameters at a time. The systems also supports FTP download of the data.

Observer Log

There is a separate stand alone system to enter information about the observation. This information is kept in an observer log. The information includes PI details, proposal details or other information like weather conditions at the time of observation. This observation log information can then be integrated with the fits file containing the observational data as additional fits headers.

System Architecture

The following figure depicts the HCT DAS Architecture

Users of HCT DAS

The system supports 4 types of users. The types of users and their data access privileges are listed below in brief.

Administrator

The administrator is the superuser of the system. There is a unique login for the ADMIN. He possesses administrative rights on the system. He does all the administrative tasks that the system requires. The tasks include creating new PI logins, making data public as per the policy, provide data for download etc.

Principal Investigator (PI)

The PI login is created by the administrator. They are the users who take the observations with the telescope. So they own the right on the data requested by them until the proprietary period expires. They can query as well as download both their own data and public data.

Registered Users

These user logins are created when users register with the system by filling a registration form. They can query as well as download public data.

Guest Users

These users don't have logins for the system. They can only query the public data.

Whenever a PI is created by the Administrator or a user registers with the system, then the system automatically sends an email to the concerned user containing his login id and password.

The figure below shows the HCT DAS registration form.

HCT DAS Administrative functions

The administrative functions for the HCT DAS are listed below.

Creating PI logins
Making data public as per policy
Change release date for specific observations.
Sanction request for data downloads
Browse through the data

The system also provides reports of lists of proposals, registered users, PI's to the administrator.

PI workflow

As mentioned in the users of the HCT DAS, the PI login is created by the administrator. They are the actual observers of the telescopic observations. The PI can login to the system, the details of which are sent to him by email after administrator creates the login. He can query his own as well as public data. The results of the query are displayed to him. He can select the data to download from this result page. The request for data download is submitted to the administrator. The administrator then copies the data to temporary storage and informs the PI via email. This step can be automated. The PI can then download the data over FTP.
The result displayed to the user has facility to display and hide the instrument specific attributes as and when required. This is achieved with the help of buttons provided, which act as a toggle for each specific instrument thus displaying or hiding the attributes.

The screen shot below shows the HFOSC instrument attributes on the result page are displayed.

The system also allows the PI to view a low resolution thumbnail image for the observation.

The figure below shows one such thumbnail image

Going Forward

The system can be improved by adding new features such as automating the transfer of data to FTP server after request is sanctioned by administrator.