The Sloan Digital Sky Survey (SDSS) and Two-Degree Field QSO Redshift Survey (2QZ) have
revealed a population of Active Galactic Nuclei (AGNs) with peculiar spectral characteristics.
These objects have featureless optical discovery spectra resembling BL Lac objects. However, they
are significantly quiet in radio and X-ray bands compared to classical BL Lacs. These objects
could therefore belong to the hitherto unrecognized population of radio-quiet BL Lacs or radio-
quiet quasars without a Broad Line Region (BLR). How such objects fit into the AGN unification
picture is an open question. Polarization and variability are the two main characteristic properties
of BL Lac objects. Last year, I was involved in two such project,first one is polarisation and
spectroscopy study of radio-quiet BL Lacs. Therefore, we selected a sample of 19 radio quiet
BL Lacs, from 2QZ and SDSS to study their polarisation, optical variability and spectroscopy.
Polarimetric and spectroscopic observations of these 19 radio quiet BL Lacs were carried out using
the 3.6m telescope at European Southern Observatory (ESO La Silla, Chile). Here we found optical
polarisation around ∼ 1% for our this sample. We did not find high polarisation (P > 3%), like BL
Lacs in our sample of radio quiet BL Lacs objects. Regards spectroscopy, we found weak emission
line in few sources. It is may be due to small sample to detect such a rare class of AGN, radio-quiet
BL Lacs. To find such a rare class, a good sample is needed. We have a sample of ∼ 40 radio-quiet
weak emission line quasars with intranight optical variability (INOV) observations and it would be
very interesting if we found BL Lacs like polarisation in these objects.
Second is continuation of our search for the elusive radio-quiet blazars, by carrying out a
systematic programme to detect intranight optical variability (INOV) in a subset of ‘Weak-Lines-
Quasars’ (WLQs) which are designated as ‘high confidence BL Lac candidates’ and are known to
be radio-quiet. For 19 such RQWLQs, we present here the INOV observations taken in 40 sessions
of durations ≥ 3.5 hours each. The 40 differential light curves (DLCs), thus obtained for the 19
RQWLQs, were subjected to an statistical analysis using the F−test and the deduced INOV char-
acteristics of the RQWLQs are compared with those published recently for several prominent AGN
classes, also using the F−test. However, since the RQWLQs are generally 1−2 magnitudes fainter,
a rigorous comparison has to wait for somewhat more sensitive INOV observations than those pre-
sented here. Based on our existing INOV observations, it seems that RQWLQs in our sample show
a significantly higher INOV duty cycle than radio-quiet quasars and radio lobe-dominated quasars.
Two sessions, when we detected rather strong (blazar-like) INOV for RQWLQs are pointed out
and both these RQWLQs are therefore candidates for radio-quiet BL Lacs.