Prof. Niranjan Thatte

Abstract:

As a prerequisite for cosmological studies using adaptive optics techniques, we have begun to identify and characterize faint sources in the vicinity of bright stars at high Galactic latitudes. The initial phase of this work has been a program of Ks imaging conducted with SOFI at the ESO NTT. From observations of 42 southern fields evenly divided between the spring and autumn skies, we have identified 391 additional stars and 1589 galaxies lying at separations Δθ ≤ 60″ from candidate guide stars in the magnitude range 9.0 ≤ R ≤ 12.4. When analyzed as a "discrete deep field" with 131 arcmin2 area, our dataset gives galaxy number counts that agree with those derived previously over the range 16 ≤ Ks < 20.5. This consistency indicates that in the aggregate, our fields should be suitable for future statistical studies. We provide our source catalogue as a resource for users of large telescopes in the southern hemisphere.

Abstract:

We present a system for the exchange and handling of cold field masks in LUCIFER, the near infrared camera and spectrograph for the LBT. Inside the LUCIFER cryostat, 10 field-stop and long-slit masks, and 23 multi-slit masks are stored in a stationary and an exchangeable cabinet respectively. With LUCIFER at operating temperature, the exchangeable cabinet with its multi-slit masks can be transferred from the LUCIFER cryostat to an auxiliary cryostat, and a second cabinet harboring the newly made, pre-cooled masks can be transferred back to LUCIFER from. a second auxiliary cryostat. Inside LUCIFER, a robot transports the individual masks from their storage position in the cabinet to the focal plane, and inserts them in a mask mount where they are centered on two pins. The position accuracy of the masks in the focal plane is anticipated to be better than +/-10 mum. A mechanism which locks the masks in their cabinets and releases only the one connected to the transport robot permits mask exchange in arbitrary orientation of the cryostat.

Abstract:

The various deep ISOCAM surveys revealed a new class of infrared luminous galaxies which are characterized by a high rate of evolution and are found at redshifts of zsimilar to1. Based on our near-infrared low-resolution spectroscopy we find that these ISOCAM galaxies are dust-enshrouded star-forming galaxies. Here we report on the first spatially resolved H. velocity profiles of ISOCAM galaxies in the Hubble Deep Field South. We find that some of these systems are in fact extremely massive galaxies. The galaxies show an offset of 1.6+/-0.3 magnitude in the rest frame B-band when compared to the local Tully-Fisher relation.

Abstract:

LUCIFER (LBT NIR-Spectroscopic Utility with Camera and Integral-Field Unit for Extragalactic Research) is a NIR spectrograph and imager for the Large Binocular Telescope (LBT) on Mt. Graham, Arizona. It is built by a consortium of five German institutes and will be one of the first light instruments for the LBT. Later, a second copy for the second mirror of the telescope will follow. Both instruments will be mounted at the bent Gregorian foci of the two individual telescope mirrors. The final design of the instrument is presently in progress.LUCIFER will work at cryogenic temperature in the wavelength range from 0.9 mum to 2.5 mum. It is equipped with three exchangeable cameras for imaging and spectroscopy: two of them are optimized for seeing-limited conditions, the third camera for the diffraction-limited case with the LBT adaptive secondary mirror working. The spectral resolution will allow for OH suppression. Up to 33 exchangeable masks will be available for longslit and multi-object spectroscopy (MOS) over the full field of view (FOV). The detector will be a Rockwell HAWAII-2 HgCdTe-array.

Abstract:

Encouraged by imaging of faint galaxies around bright stars using ALFA on the 3.5-m telescope at Calar Alto, we have begun a survey to identify a large number of candidate sources near bright stars. In this contribution we report the status of this survey and show our preliminary results from deep imaging around one of these stars during the early phases of CONICA and NAOS on the 8.2-m VLT. We outline the exciting prospects for this type of work in terms of number counts, morphology, and rotation curve analyses.