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Norwegian Astronomical Society - Variable Star Section
***** Sequence for the Cepheids TT Aquilae and SZ Aquilae *****
Compiled by Bjorn H. Granslo (version 2003 July 24)
1903+01 TT Aql [R.A. = 19h08m13s.8, Decl. = +01o17'55" (2000.0)]
1859+01 SZ Aql [R.A. = 19h04m39s.4, Decl. = +01o18'22" (2000.0)]
TT Aquilae = HD 178359 = TYC 0463-0925. GCVS (Kholopov et al. 1998) has
mag. 6.46 - 7.70 V, type DCEP, period 13.755 days and spectral type
F5-G5. The time from minimum to maximum is 34 % of period. Observations
by Berdnikov (1992) indicate a B-V colour index from +0.9 (at V = 6.5)
to +1.6 (at V = 7.6).
SZ Aquilae = HD 177441 = TYC 0462-1084. GCVS has mag. 7.92 - 9.26 V,
type DCEP, period 17.138 days and spectral type F7-K1. The time from
minimum to maximum is 37 % of period. Berdnikov (1992) has B-V from
+1.1 (at V = 8.0) to +1.8 (at V = 9.2).
The angular distance between TT Aql and SZ Aql is not more than 53'.6,
thus a common sequence is given for these stars.
*** 1. Sequence Stars ***
This list contains identifications, positions and photometry (V, B-V)
for comparison stars with B-V from -0.1 to 0.8. All stars are located
within 3-4 deg. from TT Aql and SZ Aql. For visual observations the
stars E to K should serve as suitable comparions to TT Aql, comparisons
to SZ Aql include H to R. For differential photometry with PEP or CCD
(with V and/or B filters) the preferred comparsion stars are H (near
TT Aql) and L (near SZ Aql).
Id R.A. (2000.0) Decl. Star Name V-mag sV B-V sB-V Source
h m s o ' "
A 19 13 42.7 +02 17 37 21 Aql 5.14 0.02 -0.07 0.01 GCPD
B 18 57 16.6 +02 32 07 64 Ser 5.56 0.01 0.01 0.01 GCPD
C 19 03 32.3 +01 49 08 HR 7214 5.83 0.01 0.19 0.01 GCPD
D 19 17 48.2 +02 01 54 HR 7313 6.19 0.01 0.02 0.01 GCPD
E 19 07 09.0 +00 38 28 HR 7245 6.55 0.01 0.06 0.01 GCPD
F 19 12 03.3 +02 37 21 HD 179343 6.95 0.04 0.11 0.01 GCPD
G 19 05 43.0 +04 16 43 HD 177702 7.32 0.02 0.25 0.02 Tycho-2
H 19 09 01.8 +01 21 09 HD 178574 7.56 0.01 0.46 0.01 GCPD
K 19 07 46.3 +01 47 06 HD 178240 8.11 0.02 0.24 0.03 Tycho-2
L 19 04 46.6 +01 21 28 HD 177462 8.55 0.01 0.28 0.01 GCPD
M 19 09 42.1 +01 14 05 HD 178719 8.82 0.03 0.76 0.04 Tycho-2
N 19 02 01.3 +00 41 50 HD 176808 9.08 0.03 0.37 0.04 Tycho-2
P 19 04 05.1 +01 29 38 HD 177309 9.38 0.03 0.15 0.04 Tycho-2
R 19 04 07.9 +01 24 39 BD +01 3871 9.91 0.04 0.45 0.06 ASAS-3*
S 19 04 20.2 +01 21 35 BD +01 3872 10.22 0.03 0.67 0.09 ASAS-3*
Id TYC/GSC Id TYC/GSC Id TYC/GSC Id TYC/GSC Id TYC/GSC
A 0467-4986 D 0468-3515 G 0470-1101 L 0462-1226 P 0462-0288
B 0453-0352 E 0462-1608 H 0463-2715 M 0463-1480 R 0462-1146
C 0462-0896 F 0467-2562 K 0462-1226 N 0462-1408 S 0462-0276
Notes on photometry:
Stars A-F, H and L: V magnitudes and B-V colours are derived from data
obtained at GCPD, The Lausanne Photometric Database [GCPD].
Stars G, K and M-S: V magnitudes and/or B-V colours are derived from
Tycho-2 BT and VT photometry (Hog et al. 2000) by using the
correction procedure of Bessell (2000).
Stars R-S: V is from ASAS-3, B-V is from Tycho-2 [ASAS*].
Other notes:
Star A: Variable V1288 Aql, amplitude 0.10 mag., type ACV [GCVS].
Star C: Possible variable NSV 24669, possible type DSCT [NSV].
Star F: Possible variable NSV 11799, amplitude 0.09 mag. [NSV].
Multiple system BU 1204 (comp. AB, mag. 7.5 and 7.9, sep. 0".4);
AB-C, 7.0 and 11.2, 13".0; three other stars mag. 13-14) and
STF 2476 (AB-G, 7.0 and 10.2, 31".5) [WDS].
Star G: Possible variable NSV 24683 [NSV].
Star H: Double star RST 5460, mag. 7.6 and 14.0, sep. 4".6 [WDS].
*** 2. Other Reference Stars ***
These stars - located within 35' of TT Aql or SZ Aql - may be used as
colour calibrators:
Id R.A. (2000.0) Decl. Star Name V-mag sV B-V sB-V Source
h m s o ' "
W 19 06 35.8 +01 31 20 HD 177942 7.60 0.02 1.62 0.03 Tycho-2
X 19 08 42.3 +01 49 29 HD 178481 8.60 0.02 1.34 0.05 ASAS-3*
Y 19 09 22.7 +01 13 53 BD +01 3909 9.63 0.03 1.81 0.12 ASAS-3*
Z 19 06 35.9 +01 16 58 BD +01 3888 9.68 0.03 1.40 0.10 ASAS-3*
TYC/GSC identifications: W = 0462-0296; X = 0463-0351; Y = 0463-1649;
Z = 0462-1126.
Notes:
Star W: Possible variable NSV 11741. V and B-V is from Tycho-2
w/Bessell; ASAS-3 has V = 7.62 (+/- 0.03).
Stars X-Z: V is from ASAS-3, B-V is from Tycho-2 [ASAS*].
Acknowledgements:
The VizieR Service at Centre de Donnees astronomiques de Strasbourg,
The Lausanne General Catalogue of Photometric Data (GCPD) and The All
Sky Automated Survey (ASAS) web sites have been used in preparing
this sequence.
References:
Berdnikov L. N.: 1992, "Photoelectric Observations of Cepheids in
1991", Sov. Astron. Lett., 18, 130.
Bessell M.: 2000, "The Hipparcos and Tycho Photometric System
Passbands", Publ. Ast. Soc. Pacific, 112, 961.
Hog E. et al.: 2000, "The Tycho-2 Catalogue of the 2.5 Million
Brightest Stars", Astron. Astrophys. 355, L27 [Tycho-2, TYC].
Kazarovets E. V., Durlevich O. V., Samus N. N.: 1998, "New Catalogue
of Suspected Variable Stars. Supplement - Version 1.0", Institute of
Astronomy of Russian Academy of Sciences and Sternberg Astronomical
Institute [NSV].
Kholopov P. N. et al.: 1998, "Combined General Catalogue of Variable
Stars, 4.1 Edition". The most updated version of GCVS is at
http://www.sai.msu.su/groups/cluster/gcvs/gcvs/ [GCVS].
Mermilliod J.-C., Hauck B., Mermilliod M.: "The General Catalogue of
Photometric Data", University of Lausanne, Switzerland.
URL: http://obswww.unige.ch/gcpd/gcpd.html [GCPD].
Pojmansky G.: "The All Sky Automated Survey". V magnitudes derived
from measurements with the ASAS-3 system.
URL: http://www.astrouw.edu.pl/~gp/asas/asas.html [ASAS-3].
Worley C. E., Douglass G. G.: 1996, "The Washington Visual Double Star
Catalog, 1996.0", US Naval Observatory [WDS].
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