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HALOMASTER - HaloSat Master Catalog



This table records high-level information for the observations obtained with HaloSat and provides access to the HaloSat data archive.

HaloSat is the first astrophysics-focused CubeSat funded by NASA's Astrophysics Division (PI P. Kaaret, University of Iowa). HaloSat is designed to map soft X-ray oxygen line emissions across the sky in order to constrain the mass and spatial distribution of hot gas in the Milky Way.

HaloSat was launched from the NASA Wallops Flight Facility and delivered to the International Space Station on May 21, 2018. HaloSat was deployed into orbit on July 13, 2018. The spacecraft and science instrument commissioning phase ended on October 16, 2018, and science operations started after that. Initially approved to operate for 12 months, HaloSat successfully collected science data from October 15, 2018, until September 29, 2020, effectively doubling the mission lifetime. HaloSat reentered Earth's atmosphere on January 4, 2021.

To trace the Galactic halo, HaloSat is equipped with a non-focusing instrument, comprised of three independent silicon drift detectors (SDD14, SDD38, SDD54) operating in the energy range of 0.4 - 7.0 keV with a field of view of 10 deg in diameter and an energy resolution of 84.8 +/- 2.7 eV at 677 eV and 137.4 +/- 0.9 eV at 5895 eV.

The observing strategy was to divide the sky into 333 positions (HaloSat fields) and acquire a minimum of 8000 detector-seconds for each position throughout the initial 12 months of operations. After launch, additional positions were added to the initial 333 positions.

HaloSat observations of the chosen fields are divided in intervals of time such that the data files do not exceed 2GB. Each observation is labeled with a sequence number. This database table contains one record for each sequence number and includes parameters related to the observation.

Catalog Bibcode



HaloSat: A CubeSat to Study the Hot Galactic Halo,
   Kaaret, P.,  Zajczyk A.,  LaRocca, D. M.,  Ringuette, R.,  Bluem, J.,
   Fuelberth, W., Gulick, H., Jahoda, K., Johnson, T. E., Kirchner, D. L.,
   Koutroumpa, D., Kuntz, K. D., McCurdy, R., Miles, D. M., Robison, W. T.,
   Silich, E. M., 2019, ApJ 884 162


The contents of this database table are generated at the HEASARC using information from the data files. The table was last updated in April 2023.


The unique number to identify an observation/sequence. This is a 6-digit number where the first 4-digit are the field number and the last 2-digit are the observation number of that field.

This is the designation of the pointed target. The nomenclature for the HaloSat fields is "HaloSat JHHMM+DDMM".

Right Ascension of the pointing position.

Declination of the pointing position.

Galactic Longitude of the pointing position. This parameter has been added by the HEASARC and is calculated from the J2000 pointing position.

Galactic Latitude of the pointing position. This parameter has been added by the HEASARC and is calculated from the J2000 pointing position.

The start time of the observation.

The time corresponding to the end of the observation.

The effective total observation exposure, in seconds, after data cleaning. This exposure is taken from the S14 detector cleaned event file.

The type of observation/object. Possible values and their respective meanings: SCIENCE for a normal observation either specific objects or the HaloSat fields, CALIBRATION for a calibration observations, SWCX for observations of the magnetospheric Solar Charge Exchange emission, HALO for observations of the galactic halo, EARTH for observations on dark earth.

The number of events in the HaloSat detector SDD 14 cleaned event file.

The number of events in the HaloSat detector SDD 38 cleaned event file.

The number of events in the HaloSat detector SDD 54 cleaned event file.

This parameter records the date when the data were last processed.

This records the version of the processing script used in the pipeline to generate the data products for the observation.

This records the version of the HEASoft used in the HaloSat data processing.

This records the version of the HaloSat CALDB version. This is encoded as hsYYYYMMDD, such that YYYYMMDD represents the date of the index file.

Contact Person

Questions regarding the HALOMASTER database table can be addressed to the HEASARC Help Desk.
Page Author: Browse Software Development Team
Last Modified: Thursday, 13-Apr-2023 18:48:43 EDT