We present a recent upgradation of the ARIES IMaging POLarimeter (AIMPOL) mounted on the 104[Formula: see text]cm Sampurnanand telescope of ARIES, Nainital since 2004. AIMPOL is upgraded by replacing the older detector with a new CCD, Pylon 1300B and the older sliding filter assembly with an automatic wheel filter assembly. A characterization of this CCD is performed and several CCD parameters like gain, read-out noise, dark current, and linearity are verified. The average value of the bias offset is measured to be ∼600 ADU whereas the dark current is measured to be 0.2[Formula: see text]e−/pixel/h at [Formula: see text]C. The CCD can be operated safely between [Formula: see text] C to [Formula: see text]C due to the almost constant dark current in this temperature range. The nonlinearity of the CCD is measured to be ∼2%, which is suitable for scientific observations. A few polarimetric observations are also taken using the upgraded AIMPOL. The degree of polarization and position angle of a few standard polarized stars are found to be similar to their standard and previously observed values.

We present B-, V-, R-, and I-bands linear polarimetric observations of 73 stars in the direction of open star cluster Casado Alessi 1 (hereafter Alessi 1). We aim to use polarimetry as a tool to investigate the properties and distribution of dust grains toward the direction of the cluster. The polarimetric observations were carried out using the ARIES IMaging POLarimeter mounted at the 104 cm telescope of ARIES, Nainital (India). Using the Gaia photometric data the age and distance of the cluster are estimated to be 0.8 ± 0.1 Gyr and 673 ± 98 pc, respectively. A total of 66 stars with a 26 radius from the cluster are identified as members of the cluster using the astrometric approach. Out of these 66 members, 15 stars were observed polarimetrically and found to have the same value of polarization. The majority of the stars in the region follow the general law of the polarization for the interstellar medium, indicating that polarization toward the cluster Alessi 1 is dominated by foreground dust grains. The average values of the maximum polarization (P max ) and the wavelength corresponding to the maximum polarization (λ max ) toward the cluster are found to be 0.83±0.03 % and 0.59±0.04 µm, respectively. Also, dust grains toward the cluster appear to be aligned, possibly due to the galactic magnetic field.

We present linear polarization towards the direction of the star cluster Alessi 1, which is located in the anti-galactic centre direction. We have observed the cluster using ARIES IMaging POLarimeter (AIMPOL) as a back-end instrument at 104-cm Sampuranand telescope, ARIES, Nainital. The average degree of polarization towards the cluster Alessi 1 are found to be 0.80±0.38 %, 0.80±0.23 %, 0.81±0.26 %, 0.86±0.32 %, in B, V, R, and I photometric bands, respectively, whereas the position angles are found to be 86±11o, 81±10o, 78±8o, 85±8o in B, V, R, and I bands, respectively. Polarization towards Alessi 1 cluster is dominated by foreground dust grains and probably a single layer of the polarized source appears to exist at ~ 0.7 kpc close to Alessi 1 cluster. The minor axis of dust grains towards the cluster Alessi 1 appears aligned along the galactic magnetic field.

Multiband linear polarimetric observations of 125 stars in the region of the cluster NGC 1817 have been carried out intending to study properties of interstellar dust and grains in that direction. The polarization is found to be wavelength-dependent, being maximum in the V band with an average value of 0.95%. The foreground interstellar dust grains appear to be the main source of linear polarization of starlight toward the direction of NGC 1817. The average value of the position angle in the V band of 119.°2 is found to be less than the direction of the Galactic parallel in the region, indicating that the dust grains in the direction are probably not yet relaxed. Spatial distribution of dust appears to be more diverse in the coronal region than the core region of the cluster. The maximum value of the degree of polarization is estimated to be 0.93% for members of the cluster using the Serkowski relation. The average value of wavelength corresponding to the maximum polarization of 0.54 ± 0.02 μm indicates that the size distribution of dust grains in the line of sight is similar to that of the general interstellar medium. Several variable stars in the cluster were also observed polarimetrically and pulsating variables appear to have a slightly lower value of polarization from other nonvariable member stars of the cluster. There are indications of the existence of dust layers in front of those clusters which are located close to galactic plane while for clusters located away from galactic plane no major dust layers are observed.