Double Star Measurements Using a Webcam and CCD Camera, Annual Report of 2016

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1 Page 22 Double Star Measurements Using a Webcam and CCD Camera, Annual Report of 2016 Joerg S. Schlimmer Seeheim-Jugenheim, Germany js@epsilon-lyrae.de Abstract: This report shows the results on 223 double star measurements from 2016; minimum separation is 1.23 a.s. (STF1024AB), maximum separation is 371 a.s. (STF1424AD). The mean value of all measurements is 18.7 a.s. In 2016 a total of 223 double stars were measured. In the first half of 2016, the measurements were done at the primary focus of a 12-inch Newtonian telescope with a standard webcam (Schlimmer, 2013). Its reproduction scale is about 0.77 a.s. per pixel. In the second half of 2016 the measurements were done with a CMOS QHY5L II Color camera with reproduction scale of about 0.52 a.s. per pixel. Because of longer exposure times fainter double stars could be selected. Double stars with unequal magnitudes were of particular interest. With this reproduction scale, it was found that double stars with differences of 3 magnitudes could be separated with at least 3 a.s. separation; double stars with 4 magnitude differences could be separated with at least 4 a.s. separation and so on. Figure 1 shows the 223 measurements sorted by separation. The majority of the measured doubles are closer than 7.5 as. Figure 2 shows the differences in magnitudes of the measured double stars. In 116 cases the difference is more than 2 magnitudes. Special Notes on Some Stars ES 944, WDS was discovered in 1910 by Espin and only observed in 1999 and 2015 for a second and third time (Mason, 2017). Magnitudes are 9.79 and 13.1, separation is about 5 as. A further measurement could be done in 2016 by the author. ES 528, WDS was also discovered by Espin in 1907 and observed for a second time in 2011 (Mason, 2017). Its magnitudes are and 12.7 but although my telescope had high precision positioning, I couldn t find ES 528 and I can t validate these past measurements. Close to the position of ES 528 another double star A 781 was easy to observe. Its brightness is Figure 3: ES 944 Figure 4: ES and magnitudes. Also for ES 1179, WDS there are only 2 measurements from 1912 and 1999 in the WDS catalog (Mason, 2017). Brightness is 9.63 and ES 1179 could be easy observed. Table 1 shows the measurements of separation and (Text continues on page 29)

2 Page 23 Figure 1. Separation of the 223 measurements, sorted by separation Figure 2: Differences in magnitudes, sorted by delta magnitudes

3 Page 24 Table 1. Measurements of 223 Double Stars from 2016 H 5 32AB C STT 547AB C A C STT C ES C BU 489AB C ES C BU 498AB C A C BU C A C ES C ES 408AB C ES 408CD C ES 1808AB C STI C A C BU 872AB C BRF 1AB C A C ES C ES 2083AB C A C A 1531AB W - C KUI 12AC W A 1702AB W AG 63AB W STF C AG W STF 382AB C STF 384AB C HLM 2AB C BU 787AB W BU 787AD W STF W - C STF C ES W A 989AB W A 989AC W STF 444AB C Table 1 continues on next page.

4 Page 25 Table 1 (continued). Measurements of 223 Double Stars from 2016 STF 443AB W STF W - C STF W - C STF 450AB W - C A C HLD W ES 466AB C ES 466AC C WAK 11CD C BU C STF W BU 86AB W STF 541AB W STF 541CD W STF 529AB W BU W A W BU 751AB W BU 751AC W STF W STF 716AB W STF 719AB W STF 719AC W STF W STF W STF 769AB W STF 786AB W BU W STF W A W ES W STF 905AB W ARG W STF 928AB W STF W AG W STF W J W STF 944AB W ES W Table 1 continues on next page.

5 Page 26 Table 1 (continued). Measurements of 223 Double Stars from 2016 STF W STF W H 2 71AC W STF W STF W STF1024AB W STF1033AB W AG W STF W STT W A 3061AB W S 571AC W S 571AD W STF W BKO 34DE W STF1254AB W STF1254AC W STF1254AD W STF W STF W STF1282AB W STF1297AB W STF1300AB W STF1298AB W AG W AG W STF W STT 571AB W STT 199AB W STF1342BC W STT W A W STFB 6AB W, Regulus STT W STT W STF1424AB W, γ Leo STF1424AC W STF1424AD W STF1424CD W STF W Table 1 continues on next page.

6 Page 27 Table 1 (continued). Measurements of 223 Double Stars from 2016 STF W A W STF W STF W STT 225AC W STF W STF W STF W STF W STT 237AB W STF W STF W BU W KR W STF1744AB W STF1772AB W STF W STF1826AB W STF W STF W STT C ES C A C STF1992AB-C C AG C J C A C STT C STF2142AB C STF C STF C A C HEI C STF C STF2349AB C STF2374AB C STF2374AC C STF2382AB C, Lyr STF2383CD C, Lyr A C Table 1 continues on next page.

7 Page 28 Table 1 (continued). Measurements of 223 Double Stars from 2016 STF C STFA 39AB C A C AG C STF2461AB C A 264AB C STF2487AB C HJ 2871AB C HJ 2871AC C ES C STF2579AB C STF2585AB-C C J 124AB C J 124AC C POP1228AD C POP1228AE C ES C BU 980AB C HJ 1455AC C HJ 1455AD C BU 980AE C BU 981AB C SMR C STF2613AB C A C STF C A C A C A C AG C HJ C A C STF C STF2655AB C STF2655AC C A 387AB C A 387AC C BU 442AP C BU 442BS C BU 442BT C Table 1 concludes on next page.

8 Page 29 BU 442CU C BU 442CV C A 1423AB C STF2758AH C SMR 1AI C SMR 40AO C SMR 40AP C ES C, see text A C HJ C ES C ES C A 309AB C ES C HLD C ES C ES C ES C BU 452AB C STF C STF3002AB C HJ C STF C ES C Notes: W: A webcam was used for imaging (until ) C: A CCD was used for imaging (from ) Table 1 (conclusion). Measurements of 223 Double Stars from 2016 (Continued from page 22) position angle of 223 components from Brightness and coordinates are from Washington Double Star catalog (Mason, 2016). Acknowledgements This research has made use of the Washington Double Star Catalog maintained at the U.S. Naval Observatory. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France References Schlimmer, S. Joerg, 2013, Double Star Measurements Using a Webcam, Annual Report of 2012, Journal of Double Star Observations, Vol. 9 No. 4, Mason, B.D., Wycoff, G.L. and Hartkopf, W.I, 2016, The Washington Double Star Catalog, Astrometry Department, U.S. Naval Observatory, ad.usno.navy.mil/proj/wds/