Abstract: This paper contains calibrations on the Hayes-Latham (1975) spectrophotometric system for 21 bright secondary standard stars. Seven of these calibrations are intended for use only with archival data, or the low sensitivity S1 photocathode, or both; the other 14 are for general use in the 3300 to 10,800 A wavelength range. The sky coverage of the calibrated stars is generally adequate for southern hemisphere observers, and is somewhat better than adequate for northern hemisphere observers. At wavelengths shorter than 6058 A, the calibrations include and extend the work of Breger. At wavelengths greater than 6058 A, the most frequently used data are from closely accordant data series given by Cochran (1981) and by the author. A status review is given for 'problem stars' calibrated in this and other papers. Several of these stars are small-amplitude variables, and Zeta Oph and (probably) 109 Vir vary intermittently by amounts which can be substantial. Other problems of calibration or use are discussed. Evidence is reviewed which suggests that, as a whole, the calibrations given in this paper have high accuracy. This implies that several of the calibrated stars may be used as standards each night; the advantages of this technique are described. Future work on secondary standards, and decisions which should be made about them, are reviewed.

Abstract:

The existing spectrophotometric data for the standard star 109 Vir show evidence for intermittent variation during the years 1966-68, and again after 1977. During both epochs, the variation has been of a nature to increase (b — y) and decrease m1 by roughly equal amounts. Evidence for variation of this type also appears in Strömgren data obtained by Perry during the early 1960s. The amount of this latter variation is very similar to that predicted from the later-epoch scans.

Abstract: In this paper, new spectrophotometric data are presented for the standards of the Spinrad-Taylor (1969) scanner photometric system. The new data are in the 4040-6180 A wavelength range and are used to construct a calibration of Spinrad-Taylor data to absolute units in this range. In addition, a previously published calibration for wavelengths greater than 6100 A is revised and extended through use of data in the literature. The calibrations, fused into a single whole, and the Spinrad-Taylor data themselves, are tested for systematic error, partly through use of further new spectrophotometry at wavelengths greater than 6100 A; those tests which can currently be made yield generally satisfactory results.

Abstract:

As part of our variable star follow-up program, we have examined a number of stars from the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey. Using a combination of our own data, ATLAS data, and other archival data, we confirmed the published periods and established a baseline ephemeris for each star. This initial sample of six stars are from the PUL or mono-periodic set from the ATLAS survey. Our determined periods agreed well with the published values. Five targets were found to be high amplitude δ Scuti variables (HADS), and one a low-amplitude δ Scuti (LADS). Beyond the primary period we examined the frequency content, Q value, position in the PL relation, and position within the instability strip of each object. We found ATO J070.9950+37.4038 to be the most complex target. The frequency content is likely a set of nonradial pulsations. ATO J328.8034+58.0406 is a multiperiodic HADS variable that is pulsating in the first and second overtones. ATO 345.4240+42.0479 was found to be a simple HADS monoperiodic fundamental pulsator. In the case of ATO J086.0780+30.3287, we found a strong fundamental pulsation with many harmonics and a weaker first overtone pulsation. We classify ATO J086.0780+30.3287 as a HADS. ATO J077.6090+36.5619 was found to be an interesting case of a monoperiodic star that appears to be pulsating in the third overtone. The lower amplitude for this target would put it in the LADS group. ATO J045.8159+46.0090 was found to be a multiperiodic HADS pulsating in the first and second overtones.

Abstract:

We present the discovery and characterization of six short-period, transiting giant planets from NASA’s Transiting Exoplanet Survey Satellite (TESS) — TOI-1811 (TIC 376524552), TOI-2025 (TIC 394050135), TOI-2145 (TIC 88992642), TOI-2152 (TIC 395393265), TOI-2154 (TIC 428787891), & TOI-2497 (TIC 97568467). All six planets orbit bright host stars (8.9 <G < 11.8, 7.7 <K < 10.1). Using a combination of time-series photometric and spectroscopic follow-up observations from the TESS Follow-up Observing Program (TFOP) Working Group, we have determined that the planets are Jovian-sized (RP = 0.99-1.45 RJ), have masses ranging from 0.92 to 5.26 MJ, and orbit F, G, and K stars (4766 ≤ Teff ≤ 7360 K). We detect a significant orbital eccentricity for the three longest-period systems in our sample: TOI-2025 b (P = 8.872 days, 0.394$^{+0.035}_{-0.038}$), TOI-2145 b (P = 10.261 days, e = $0.208^{+0.034}_{-0.047}$), and TOI-2497 b (P = 10.656 days, e = $0.195^{+0.043}_{-0.040}$). TOI-2145 b and TOI-2497 b both orbit subgiant host stars (3.8 < log  g <4.0), but these planets show no sign of inflation despite very high levels of irradiation. The lack of inflation may be explained by the high mass of the planets; $5.26^{+0.38}_{-0.37}$ MJ (TOI-2145 b) and 4.82 ± 0.41 MJ (TOI-2497 b). These six new discoveries contribute to the larger community effort to use TESS to create a magnitude-complete, self-consistent sample of giant planets with well-determined parameters for future detailed studies.

Abstract:

As part of our variable star follow-up program we have examined a number of stars from the ATLAS (Asteroid Terrestrial-impact Last Alert System) survey. The first of these, ATO J031.2309+52.9923, was reported with a period of 0.069705 d. Our revised period is 0.06970555 d, but we find an additional period of 0.074 d. We also report a suspected period change of (1 / P) dP / dT = –340 × 10–8 yr–1. In addition to the primary period, we find two additional closely spaced periods of 0.07380 d and 0.07338 d, with a period ratio of P1 / P2 = 0.945. The period ratio and change would indicate that this object is a δ Scuti variable with non-radial pulsations. We find that this target fits into the medium amplitude group of δ Scuti variables such as AN Lyncis.