T. P. Prabhu

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses - XII. Time delays of the doubly lensed quasars SDSS J1206+4332 and HS 2209+1914

Aims. Within the framework of the COSMOGRAIL collaboration we present 7- and 8.5-year-long light curves and time-delay estimates for two gravitationally lensed quasars: SDSS J1206+4332 and HS 2209+1914. Methods. We monitored these doubly lensed quasars in the R-band using four telescopes: the Mercator, Maidanak, Himalayan Chandra, and Euler telescopes, together spanning a period of 7 to 8.5 observing seasons from mid-2004 to mid-2011. The photometry of the quasar images was obtained through simultaneous deconvolution of these data. The time delays were determined from these resulting light curves using four very di erent techniques: a dispersion method, a spline fit, a regression di erence technique, and a numerical model fit. This minimizes the bias that might be introduced by the use of a single method. Results. The time delay for SDSS J1206+4332 is tAB = 111:3 3 days with A leading B, confirming a previously published result within the error bars. For HS 2209+1914 we present a new time delay of tBA = 20:0 5 days with B leading A. Conclusions. The combination of data from up to four telescopes have led to well-sampled and nearly 9-season-long light curves, which were necessary to obtain these results, especially for the compact doubly lensed quasar HS 2209+1914.

A multiwavelength study of the massive star forming region iras 06055+2039 (rafgl 5179)

Aims. We present a multiwavelength study of the massive star-forming region associated with IRAS 06055+2039. Methods. Narrow-band near-infrared (NIR) observations were carried out with UKIRT-UFTI in molecular hydrogen and Br γ lines to trace the shocked and ionized gases, respectively. We have used 2MASS

H0 from ten well-measured time delay lenses

{it J H K}_{rm s}

MULTI-FREQUENCY, MULTI-EPOCH STUDY OF Mrk 501: HINTS FOR A TWO-COMPONENT NATURE OF THE EMISSION

data to study the nature of the embedded cluster associated with IRASxa006055+2039. The radio emission from the ionized gas was mapped atxa0610 and 1280xa0MHz using the Giant Metrewave Radio Telescope (GMRT), India. Emission from warm dust and the unidentified infrared bands (UIBs) was estimated using the mid-infrared (8–21u2009 μ m) data from the MSX survey. Submillimetre emission from the cold dust atxa0450 and 850u2009 μ m was studied using JCMT-SCUBA. Results. For the infrared cluster associated with IRAS 06055+2039, we obtain a power-law slope of

Giant Metrewave Radio Telescope Observations of the 2006 Outburst of the Nova RS Ophiuchi: First Detection of Emission at Radio Frequencies <1.4 GHz

0.43pm0.09

Radio Continuum and H I Study of Blue Compact Dwarf Galaxies

for the K s -band luminosity function (KLF), which is in good agreement with other young embedded clusters. We estimate an age of 2–3xa0Myr for this cluster. Apart from the diffuse emission, the high-resolution 1280xa0MHz map also shows the presence of several discrete sources that possibly represent high-density clumps. The morphology of shocked molecular hydrogen forms an arc towards the N-E of the central IRAS point source and envelopes the radio emission. Submillimetre emission shows the presence of a dense cloud core that is probably at an earlier evolutionary stage compared to the ionized region with shocked molecular gas lying between the two. The total mass of the cloud is estimated to be ~7000–9000xa0

Long-term study of Mkn 421 with the HAGAR Array of Telescopes

M_{odot}

Pointing of HAGAR telescope mirrors

from the submillimetre emission atxa0450 and 850u2009 μ m. Conclusions. The multiwavelength study of this star-forming complex reveals an interesting scenario where regions are at different stages in the evolution of star formation.

The Himalayan Gamma Ray Observatory at Hanle

In this work, we present a homogeneous curve-shifting analysis of the publicly available light curves of 24 gravitationally lensed quasars, for which time delays have been reported in the literature till date, using the di erence-smoothing technique. The uncertainty of each measured time delay was estimated using realistic simulated light curves. The recipe for generating such simulated light curves with known time delays in a plausible range around the measured time delay is introduced here. We identified 14 gravitationally lensed quasars that have light curves of su ciently good quality to enable the measurement of at least one time delay between the images, adjacent to each other in terms of arrival-time order, to a precision of better than 20% (including systematic errors). We modelled the mass distribution of 10 of those systems, which have known lens redshifts, accurate astrometric data and su ciently simple mass distribution, using the publicly available PixeLens code to infer a value of H0 of 68.1 5.9 km s 1 Mpc 1 (1 uncertainty, 8.7% precision) for a spatially flat universe having m = 0.3 and = 0.7. We note here that the lens modelling approach followed in this work is a relatively simple one and does not account for subtle systematics such as those resulting from line of sight e ects and hence our H0 estimate should be considered as indicative.

Gamma-Ray Source Observations with the HAGAR telescope system at Hanle in the Himalayas

Since the detection of very high energy (VHE)