V345 Lac

TESS eclipses near V345 Lac

TIC 421726141 · TYC 3986-02900-1 · Gaia DR3 2005071229786849664

Position
22h 18m 43.3s, +54° 40′ 33.5″
V magnitude
11.25
Where
Center of the search. Already a known eclipsing binary
Signal
Eccentric EA, known since before this search. Primary about 36 percent. Secondary about 38 percent, and deeper.

What TESS shows

V345 Lacertae is the known eccentric eclipsing binary this search is centered on. The page is a timing check of that published star. TESS 120-second PDCSAP flux with quality flag exactly zero, in sectors 56, 57, 76, 77, 83, and 84, times 20 primary minima and 17 secondary minima. The linear ephemeris is

Min I = BTJD 2828.5708 + 7.4919092 E

The period is 7.4919092 ± 0.0000043 days. It agrees with the Wolf et al. (2019) sidereal period, 7.49190587 days, to about 0.3 seconds. The primary fades by about 36 percent. The secondary fades by about 38 percent, so the secondary is the deeper minimum. It falls at phase 0.358. At the middle of the TESS series the primary-to-secondary gap is 2.6815 days. Periastron is near phase 0.25. Those timings match e = 0.260 and ω = 208.3°, with e cos ω = −0.223.

From sectors 56 and 57 to sectors 83 and 84 the gap grew from 2.6785 days to 2.6835 days, which is 7.2 minutes, or 3.6 ± 0.4 minutes per year. Wolf et al. predicted 3.4 minutes per year. Primary times scatter by 1.1 minutes rms. The minimum at BTJD 3420.429, just after the Sector 77 gap, is 3.3 minutes early.

Two years of TESS times are too short to measure the apsidal period, U = 1580 ± 610 years, or the 23.9-year light-time orbit. The note does not file a new star.

The diagrams

Sectors 56 and 57. Red marks are primary minima. Blue marks are secondary minima. Quality flag zero only.
Sectors 56 and 57. Red marks are primary minima. Blue marks are secondary minima. Quality flag zero only.
Sectors 76 and 77. One primary falls in the gap after the sector boundary and was not timed.
Sectors 76 and 77. One primary falls in the gap after the sector boundary and was not timed.
Sectors 83 and 84. The secondary stays the deeper eclipse.
Sectors 83 and 84. The secondary stays the deeper eclipse.
Folded on the TESS period. Primary minimum is at phase 0. Secondary minimum is at phase 0.358. Periastron is the dotted line near phase 0.25.
Folded on the TESS period. Primary minimum is at phase 0. Secondary minimum is at phase 0.358. Periastron is the dotted line near phase 0.25.
Primary residuals about the linear ephemeris. The scatter is 1.1 minutes. The amber point is BTJD 3420.429, after the Sector 77 gap.
Primary residuals about the linear ephemeris. The scatter is 1.1 minutes. The amber point is BTJD 3420.429, after the Sector 77 gap.

Finder chart

Real sky images (DSS2 red) with Gaia DR3 stars overlaid. North is up, east is left, J2000. Red tick marks point at the target (Gaia DR3 2005071229786849664, G = 11.25). Gold squares C1 to C5 are comparison stars of similar brightness. Tap an image for the full-size printable chart.

V345 Lac Wide finder, 30 × 30 arcmin, for star-hopping.
Wide finder, 30 × 30 arcmin, for star-hopping.
V345 Lac Close finder, 8 × 8 arcmin, to pick out the target.
Close finder, 8 × 8 arcmin, to pick out the target.
Gaia DR3RA, Dec (J2000)GBPRPFrom target
C1200507305086113024022:18:39.7 +54:43:12.211.2411.3311.062.7′
C2200505989108139392022:19:02.6 +54:38:15.311.8611.9311.703.6′
C3200507098926806579222:18:10.5 +54:39:01.911.8611.9411.695.0′
C4200507098927831091222:18:11.1 +54:38:43.210.8510.9510.655.0′
C5200505817309448396822:18:46.4 +54:35:06.910.6110.6710.485.5′

Comparison stars are within about 1 mag of the target in Gaia G, have similar color, no close companion, and no VSX entry within 10 arcsec. Images: DSS2 red (POSS-II, STScI Digitized Sky Survey). Stars: ESA Gaia DR3.

VSX

Already in the catalogs as an eclipsing binary. This note does not file a new star. It checks the Wolf et al. (2019) orbit with TESS times from 2022 to 2024.

Reference ephemeris

  1. Eclipse 1Primary minimum. 4 Nov 2026, 22:11 UTC · 4 Nov, 14:11 PST Pacific · 4 Nov, 23:11 CET central Europe
  2. Eclipse 2Secondary minimum, the deeper one. 7 Nov 2026, 14:44 UTC · 7 Nov, 06:44 PST Pacific · 7 Nov, 15:44 CET central Europe

The secondary follows the primary by about 2.68 days, and that gap grows by about 3.6 minutes per year. These clocks are good to a few minutes. The secondary is the deeper minimum. This is a reference ephemeris for a well-established binary. It is not a request for observations.

The note

V345 Lacertae: TESS Eclipse Timings and the Apsidal Drift of the Secondary Minimum (PDF)

These pages use the public TESS Quick-Look Pipeline and catalog positions. The times above are a reference ephemeris for a well-established binary.