William Optics RedCat 51 (51 mm aperture, 250 mm focal length); ZWO ASI1600MM Pro, gain 139, offset 10, 1x1 binning, -10 C. Optolong 1.25-inch H-alpha 7 nm, [O III] 6.5 nm and [S II] 6.5 nm filters; ZWO EFW.
CL Aur, 2026-10-17 UTC; 14 retained exposures through H-alpha. Optolong 1.25-inch narrowband filter; nominal FWHM 7 nm (HASIIOIII-125 set). JD values are UTC exposure midpoints, uncorrected (not HJD/BJD). Relative ensemble magnitudes: this target's Oct 18 median is set to zero separately in each filter. This reference level is not a verified out-of-eclipse maximum; these are not standard magnitudes. Filters must remain separate.
Native-pixel dark/flat calibrated aperture photometry: radius 5 px (~15.8 arcsec), sky annulus 12-18 px; checked at 7/9 px and with an independent ensemble. Clouds/uncertain intervals excluded. Satellite-trail affected comparison measurements masked; target aperture unaffected.
Empirical check-star uncertainty (mag), in file row order: 0.0672, 0.0395, 0.0395, 0.0395, 0.0395, 0.0395, 0.0395, 0.0395, 0.0674, 0.0673, 0.0566, 0.0505, 0.0467, 0.0395.
Finding-chart labels below map local field IDs to Gaia DR3 source IDs. Gaia magnitudes identify stars only, not narrowband calibration. C=comparison ensemble; K=independent checks.
C: 828=181924987776412032, 2069=181904818609997568, 2048=182124278554551808, 483=182124381633760384, 1816=181532187246360192, 1488=181914061379613440, 794=181920628384666496, 2027=181915680582371584, 751=181859021373889664, 1131=181531568771070592, 1802=181903341138928000, 1445=181956358216236416, 667=181529889439234816, 411=181527651760898432, 883=181944778984398208, 461=181863934816447744, 1466=181867847531508736, 381=181864450212510720, 1841=182149704760896128, 1876=181938873405714816.
K: 1338=181962061932803456, 682=181938598527811712, 1618=182150323236181120, 2003=181852527383372032, 1144=182151177931992320, 684=181939079564130816, 806=181853145858644352, 442=181477937515914368, 2248=181941931422379392, 818=182151796407282560, 1120=181861804512632704, 1261=181851427871877120, 591=181476150808390912, 808=181852733541800320, 2078=181940724536592640, 620=181841600986534400, 532=182154893081375232, 1087=181947527763469824, 584=182167640544313344, 1368=182152689760476416.
Oct 17 shows a likely secondary eclipse. No precision minimum, period change or discovery is claimed. Raw frames, calibrations, rich CSVs and full reduction provenance are retained.

William Optics RedCat 51 (51 mm aperture, 250 mm focal length); ZWO ASI1600MM Pro, gain 139, offset 10, 1x1 binning, -10 C. Optolong 1.25-inch H-alpha 7 nm, [O III] 6.5 nm and [S II] 6.5 nm filters; ZWO EFW.
CL Aur, 2026-10-17 UTC; 14 retained exposures through H-alpha. Optolong 1.25-inch narrowband filter; nominal FWHM 7 nm (HASIIOIII-125 set). JD values are UTC exposure midpoints, uncorrected (not HJD/BJD). Relative ensemble magnitudes: this target's Oct 18 median is set to zero separately in each filter. This reference level is not a verified out-of-eclipse maximum; these are not standard magnitudes. Filters must remain separate.
Native-pixel dark/flat calibrated aperture photometry: radius 5 px (~15.8 arcsec), sky annulus 12-18 px; checked at 7/9 px and with an independent ensemble. Clouds/uncertain intervals excluded. Satellite-trail affected comparison measurements masked; target aperture unaffected.
Empirical check-star uncertainty (mag), in file row order: 0.0672, 0.0395, 0.0395, 0.0395, 0.0395, 0.0395, 0.0395, 0.0395, 0.0674, 0.0673, 0.0566, 0.0505, 0.0467, 0.0395.
Finding-chart labels below map local field IDs to Gaia DR3 source IDs. Gaia magnitudes identify stars only, not narrowband calibration. C=comparison ensemble; K=independent checks.
C: 828=181924987776412032, 2069=181904818609997568, 2048=182124278554551808, 483=182124381633760384, 1816=181532187246360192, 1488=181914061379613440, 794=181920628384666496, 2027=181915680582371584, 751=181859021373889664, 1131=181531568771070592, 1802=181903341138928000, 1445=181956358216236416, 667=181529889439234816, 411=181527651760898432, 883=181944778984398208, 461=181863934816447744, 1466=181867847531508736, 381=181864450212510720, 1841=182149704760896128, 1876=181938873405714816.
K: 1338=181962061932803456, 682=181938598527811712, 1618=182150323236181120, 2003=181852527383372032, 1144=182151177931992320, 684=181939079564130816, 806=181853145858644352, 442=181477937515914368, 2248=181941931422379392, 818=182151796407282560, 1120=181861804512632704, 1261=181851427871877120, 591=181476150808390912, 808=181852733541800320, 2078=181940724536592640, 620=181841600986534400, 532=182154893081375232, 1087=181947527763469824, 584=182167640544313344, 1368=182152689760476416.
Oct 17 shows a likely secondary eclipse. No precision minimum, period change or discovery is claimed. Raw frames, calibrations, rich CSVs and full reduction provenance are retained.

Sky-Watcher NWT 254/1200 + CCD QHY 174
předpověď primárního minima JDhel=2458922.3145 - 19h32m UT (Mo=51956.3593 per.= 1.244365 dne) - minimum nastalo o 2h12m později

Sky-Watcher NWT 254/1200 + CCD QHY 174

----- EBFit result: -----
Tmin = 2458922.40572
Error (1 sigma): +0.00006/-0.00006 (Bootstrapping), +0.00007/-0.00006 (Prayer bead), +0.00002/-0.00002 (LSM)
Error (95% CI): +0.00012/-0.00012 (Bootstrapping), +0.00010/-0.00009 (Prayer bead)
LSM: chi^2 = 2047.3, n_freedom = 192

Skywatcher Evostar 80ED ASI-385MCC
----- EBFit result: -----
Tmin = 2458499.31444
Error (1 sigma): +0.00020/-0.00017 (Bootstrapping), +0.00011/-0.00013 (Prayer bead), +0.00027/-0.00027 (LSM)
Error (95% CI): +0.00035/-0.00035 (Bootstrapping), +0.00018/-0.00018 (Prayer bead)
LSM: chi^2 = 51.3, n_freedom = 110

Newton RL 150/750 + SBIG ST7, autoguiding G1 0300 (sekční set)


----- EBFit result: -----
Tmin = 2456269.38276
Error (1 sigma): +0.00007/-0.00006 (Bootstrapping), +0.00004/-0.00004 (Prayer bead), +0.00009/-0.00009 (LSM)
Error (95% CI): +0.00014/-0.00013 (Bootstrapping), +0.00012/-0.00008 (Prayer bead)
LSM: chi^2 = 42.9, n_freedom = 68

200/1 000, ST-9E
TminHJD = 2456004.33406 +/- 0.000056 primary minimum

Celestron 355/2460mm + CCD ST7
předpověď primárního minima JDg=2455867.3942 - 21h27m UT (Mo=51956.3593 per.=1.244365 dne) - minimum nastalo o 1h17m později

Celestron 280/1765 + CCD G2 1600
předpověď primárního minima - 2455561.2794 - 18h42m UT (podle Mo=51956.3593 per.=1.244365 dne) - minimum nastalo o 1h09m později

Celestron 280/1765 + CCD G2 1600
předpověď primárního minima - 2455561.2794 - 18h42m UT (podle Mo=51956.3593 per.=1.244365 dne) - minimum nastalo o 1h09m později

0.40-m f/5 + CCD ST7 + R
# NAME CL Aur
# VAR 05:12:54.2 +33:30:28 2432967.256 1.2443718 12.1-13.2 (O-C gateway 20090103)
# OBS Martin Lehky (Hradec Kralove CZ; 0.40-m f/5 reflector + CCD ST7)
# FLT R
# RED CMunipack 1.1.24 + AVE 2.51
# NOTE 02/03 I 2009; R_465_30s (444/266); minimum P
# NOTE 2454834.60831 +/- 0.00010; 20090103 02:35:08 (UT) GEO
# COND somewhat cloudy -> clear weather -> foggy weather and frost cover

0.40-m f/5 + CCD ST7 + R
# NAME CL Aur
# VAR 05:12:54.2 +33:30:28 2432967.256 1.2443718 12.1-13.2 (O-C gateway 20090103)
# OBS Martin Lehky (Hradec Kralove CZ; 0.40-m f/5 reflector + CCD ST7)
# FLT R
# RED CMunipack 1.1.24 + AVE 2.51
# NOTE 02/03 I 2009; R_465_30s (444/266); minimum P
# NOTE 2454834.60831 +/- 0.00010; 20090103 02:35:08 (UT) GEO
# COND somewhat cloudy -> clear weather -> foggy weather and frost cover

Celestron 280/1765 + CCD ST7
předpověď prim. min. JDg=2454843,2813 - 18h45m UT, minimum nastalo o 51 minut později (podle Mo=51956,3593 per.= 1,244365)

Celestron 280/1765 + CCD ST7
předpověď prim. min. JDg=2454843,2813 - 18h45m UT, minimum nastalo o 51 minut později (podle Mo=51956,3593 per.= 1,244365)

0.25-m f/5 + CCD ST5C + V
# NAME CL Aur
# VAR 05:12:54.2 +33:30:28 2451956.3593 1.244365 12.1-13.2 (BRKA 2005)
# OBS Martin Lehky (Hradec Kralove CZ; 0.25-m f/5 reflector + CCD ST5C)
# FLT V
# RED CMunipack 1.1.3 + AVE 2.51 (Martin Lehky 04 VII 2007)
# NOTE 22/23 XII 2000; V_110_60s (104/50); minimum
# NOTE 2451901.60186 +/- 0.00025; 20001223 02:26:41 (UT) GEO

0.25-m f/5 + CCD ST5C + V
# NAME CL Aur
# VAR 05:12:54.2 +33:30:28 2451956.3593 1.244365 12.1-13.2 (BRKA 2005)
# OBS Martin Lehky (Hradec Kralove CZ; 0.25-m f/5 reflector + CCD ST5C)
# FLT V
# RED CMunipack 1.1.3 + AVE 2.51 (Martin Lehky 04 VII 2007)
# NOTE 22/23 XII 2000; V_110_60s (104/50); minimum
# NOTE 2451901.60186 +/- 0.00025; 20001223 02:26:41 (UT) GEO

0.25-m f/5 + CCD ST5C + V
# NAME CL Aur
# VAR 05:12:54.2 +33:30:28 2451956.3593 1.244365 12.1-13.2 (BRKA 2005)
# OBS Martin Lehky (Hradec Kralove CZ; 0.25-m f/5 reflector + CCD ST5C)
# FLT V
# RED CMunipack 1.1.3 + AVE 2.51 (Martin Lehky 04 VII 2007)
# NOTE 13/14 XII 2000; V_50_60s (33); steady

0.25-m f/5 + CCD ST5C + V
# NAME CL Aur
# VAR 05:12:54.2 +33:30:28 2451956.3593 1.244365 12.1-13.2 (BRKA 2005)
# OBS Martin Lehky (Hradec Kralove CZ; 0.25-m f/5 reflector + CCD ST5C)
# FLT V
# RED CMunipack 1.1.3 + AVE 2.51 (Martin Lehky 04 VII 2007)
# NOTE 01/02 XII 2000; V_28_60s (24); minimum
# NOTE 2451880.44705 +/- 0.00021; 20001201 22:43:45 (UT) GEO

0.25-m f/5 + CCD ST5C + V
# NAME CL Aur
# VAR 05:12:54.2 +33:30:28 2451956.3593 1.244365 12.1-13.2 (BRKA 2005)
# OBS Martin Lehky (Hradec Kralove CZ; 0.25-m f/5 reflector + CCD ST5C)
# FLT V
# RED CMunipack 1.1.3 + AVE 2.51 (Martin Lehky 04 VII 2007)
# NOTE 01/02 XII 2000; V_28_60s (24); minimum
# NOTE 2451880.44705 +/- 0.00021; 20001201 22:43:45 (UT) GEO

Celestron 280/1765 + CCD ST7
Předpověď prim. minima JDg = 2454558,3287 - 19h53m UT (podle Mo=51956,3593 per.=1.244365)
minimum nastalo o 45 minut později (v souladu s O-C grafem)

RL 0.2m, f/10 + ST-8
TminGJD = 2454070.55103 +/- 0.0001
TminHJD = 2454070.55658 +/- 0.0001
HELcor = 0.00555d
TimePCerror = 2.2 +/- 0.1s
CCD+R