Table 1 Observing log and polarimetric measurements of comet 2I/Borisov.

From: Unusual polarimetric properties for interstellar comet 2I/Borisov

DATE

UT

\({t}_{\exp }\)

FILTER

r

Δ

α

Pr = Q/I

U/I

Notes

  

(s)

 

(a.u.)

(a.u.)

()

(%)

(%)

 

2019-12-25

08:02

880

VF

2.04

1.94

28.48

3.35 ± 0.07

−0.01 ± 0.07

2019-12-25

08:24

480

RF

3.76 ± 0.08

0.17 ± 0.08

2019-12-25

08:39

360

IF

4.14 ± 0.14

−0.03 ± 0.14

2020-01-08

08:05

1280

VF

2.12

1.95

27.56

2.59 ± 0.06

0.14 ± 0.06

2020-01-08

08:34

720

RF

3.32 ± 0.18

0.20 ± 0.10

a

2020-02-06

08:17

1280

IF

2.40

2.12

24.14

1.37 ± 0.28

−0.88 ± 0.32

b

2020-02-06

08:46

1440

RF

1.19 ± 0.21

0.03 ± 0.21

b

2020-02-17

04:12

1280

IF

2.54

2.21

22.63

1.14 ± 0.18

0.11 ± 0.18

2020-02-17

04:24

1440

RF

0.53 ± 0.19

−0.08 ± 0.14

2020-03-20

03:14

1120

VF

3.02

2.53

18.06

−1.05 ± 0.15

0.09 ± 0.16

2020-03-20

03:41

1440

RF

−0.82 ± 0.13

0.25 ± 0.10

  1. Table is organised as follows: observing date and time (cols. 1 and 2); exposure time (col. 3); the filter used for the observations (col. 4); the heliocentric distance r and geocentric distance Δ to the comet (cols. 5 and 6, respectively); the phase angle (col. 7); the reduced Stokes parameters Q/I and U/I (cols. 8 and 9). Column 10 refers to special table footnotes. Effective wavelength and bandwidths as follow: filter VF is centred at 557 nm with a 123-nm FWHM; filter RF is centred at 655 nm with a 165-nm FWHM; filter IF is centred at 768 nm with a 138-nm FWHM.
  2. aA background star was very close to the comet photocentre during the exposures with retarder waveplate at PA = 22. 5, 45, 67. 5, which were discarded from the analysis.
  3. bData were obtained with very poor seeing and in a very crowded background. See notes in the text.