Download TIRCAM2 (TIFR Near Infrared Imaging Camera - II) @ 3.6m

TIRCAM2 (TIFR Near Infrared Imaging Camera - II) @
3.6m DOT
TIRCAM2 (TIFR Near Infrared Imaging Camera - II) is a closed cycle cooled imager
that has been developed by the Infrared Astronomy Group at the Tata Institute of
Fundamental Research for observations in the near infrared (NIR) band of 1 to 3.7
μm.
TIRCAM2 is sensitive up to 3.8 μm and contains selectable standard NIR filters J, H,
Kcont, K, Br-Gamma, polycyclic aromatic hydrocarbon (PAH) and nbL for
imaging. TIRCAM2 uses a 512 x 512 InSb based Aladdin III Quadrant focal plane
array. It is cooled by a closed cycle Helium cryo-cooler to 35 K while operating.
TIRCAM2 is currently the only NIR imaging camera in the country which can observe
up to L band in NIR.
Table 1: TIRCAM2 Filter Characteristics
Filter
λcen (μm)
∆λ (μm)
J
1.20
0.36
H
1.60
0.30
Br-Gamma
2.16
0.03
K
2.19
0.40
Kcont
2.17
0.03
PAH
3.27
0.06
nbL
3.59
0.07
Expected limiting magnitudes achievable with TIRCAM2 on 3.6m DOT
17 mag in J and 15.3 mag in K (for 1000s and 150s exposures, respectively), and 5
mag in nbL band (for 0.5 sec net exposure) in a typical seeing condition.
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The FoV of TIRCAM2 on DOT is 86.5 x 86.5 arcsec2
Pixel Scale of TIRCAM2 on DOT is 0.169 +/- 0.002 arcsec / pixel
With a typical 1.2 arcsec seeing condition, TIRCAM2 heavily oversamples the star
profile. This pixel sampling is ideal for high accuracy photometry of bright NIR
sources.
Dark current is 12 e − /sec and the readout noise is ∼30 electrons.
For details of the TIRCAM2 instrument and calibration see paper :
Naik, M. B., et al. ‘TIRCAM2: The TIFR Near Infrared Imaging Camera’. Bull. Astr.
Soc. India (BASI) 40 (2012): 531–545.
Optimal Observation Strategy
The observation procedure on TIRCAM2 is mostly standard NIR observation
strategy which involves taking flats in the morning and evening twilight. Dithered
short exposure observations of the target star as well as nearby NIR photometric
standard star with 5-point dithered pattern is sufficient. Only additional step needed
in TIRCAM2 observation is additional blank sky images of identical exposures. This
is to remove a non-uniform additive illumination in TIRCAM2 images. During data
reduction they are to be removed by subtracting these blank sky images before the
flat-fielding step.
Caption: Filter transmission curves of TIRCAM2 (at present H2 narrow band filter is not
available in TIRCAM2 due to limited slots in the filter wheel).
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Caption: TIRCAM2 mounted on DOT on 1 June 2016.
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Caption: Saturn image taken using TIRCAM2 on DOT on 2 June 2016.
J Filter : Exposure ~ 5 sec.
H Filter : Exposure ~ 5 sec.
K Filter : Exposure ~ 5 sec.
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TIRCAM2 observations were carried out from Devasthal Optical Telesceope for window 7 to
17 January 2017. TIRCAM2 was ready for observations from 9Jan2017 on the telescope.
Balancing was carried out on 9Jan2017. Out of 6 nights, some observations could be done
on 3 nights, due to problems such as cloudy nights, high humidity and few telescope
problems such as mirror actuator errors, pointing problems, drifts, distorted images etc. Due
to such conditions systematic data collection could not be done.
Considering above conditions in data collection, some preliminary data processing
was done and images are reported here.
Hubble Aug2000 NIR
Trapezium
1.6, 1.1 micron
DOT -TIRCAM2 Jan2017, Trapezium
K filter, 2.19 micron , 0.256 Sec.
DOT -TIRCAM2 Jan2017, Trapezium
K filter, 2.19 micron , ~ 25 Sec.
2mass, Trapezium, K filter,
Circled is a 11.049 magnitude star.
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DOT -TIRCAM2 Jan2017,
HD41827 J-filter, ~ 2.3 Sec.
DOT -TIRCAM2 Jan2017,
Jupiter, Callisto , K-filter, ~ 1.3 sec.
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