Information for Observers

As part of our planned BLAST-TNG Antarctic science campaign in December 2017, the BLAST collaboration is alocating 25% of the total available science time to observing proposals from the astronomical community. Note that these will be shared-risk proposals – observations will only be carried out if warranted by the in-flight performance characteristics of BLAST-TNG, as determined by the BLAST team after launch. Observations, data reduction, and production of science-quality maps will be carried out by the BLAST team on a best effort basis and with the understanding that BLAST team members will be co-authors on publications resulting from the observations.

BLAST-TNG observes simultaneously in three frequency bands centered at 250, 350 and 500 μm. An estimate for the mapping speed and resolution at each frequency band is given below. Assuming a 25-day flight, we expect to allocate approximately 125 hours of time to shared-risk proposals received from the astronomical community.

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Expected Mapping Speed

Based on our experience with BLASTPol we expect the following mapping speeds. In early 2017 we will be performing extensive testing of our detector arrays and readout system, so these numbers will be updated before the call for proposals in April 2017.

Central Wavelength [μm] 250 350 500
Beam FWHM [‘’] 25 35 50
σI (for a 1.0 deg2 map observed for 5 hours) [MJy Str-1] 0.39 0.21 0.08
Iminp =0.5%, time=5 hours, map area= 1.0 deg2)

[MJy Str-1]

220 117 44

Note: For a given map area and time observing the map (in the table we chose an area of 1.0deg2) Imin gives the minimum dust intensity for which the error in fractional polarization (σp) is less than 0.5%.

Sky Visiblity from Antarctica

BLAST-TNG is restricted to observe with the telescope elevation between about 20 to 55 degrees.  The allowed range of telescope azimuth is set by the requirement that radiation from the sun does not reach the primary mirror.  The region of the sky available to BLAST-TNG therefore will change over the course of the flight.  Changes in latitude of the telescope as the balloon travels around Antarctica will also affect visibility.

infoforobs1

Expected visibility for BLAST-TNG on December 22nd 2017 at a latitude of -77.5 degrees (approximately the same as McMurdo Station). The visibility represents the total number of hours that each map pixel is visible in a 24 hour period. The background image shows the Galactic Plane dust distribution from the SFD models.

infoforobs2

Expected visibility for BLAST-TNG on January 21st 2018 at a latitude of -77.5 degrees (approximately the same as McMurdo Station). The visibility represents the total number of hours that each map pixel is visible in a 24 hour period. The background image shows the Galactic Plane dust distribution from the SFD models.

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