x 1 2 m 5 1 0 ~ 4 ~ 3 5 ? 4 7 +26O 56' 2Y7 I y I I 10 4 40.58 +26 56 8 . 7 . I

Der Ort von +26"2058 stimmt vollig innerhalb seiner Un- sicherheit mit dem von x iiberein; von y weicht er in RA. schon etwas zu stark ab. Beide Sterne sind itbrigens so schwach, dafi keine Rede davon sein kann, ihr vereintes Licht habe etwa den Eindruck von +26O2058 erzeugt. Ich hake es far nicht unmoglich, da13 +26O2058 verinderlich und mit x identisch ist; er mag in BD. den Vermerk var.? erhalten und verdient weiter verfolgt zu werden.

Der Stern BD. +27O1861 9m4 1 0 ~ 5 ~ 3 5 ? 1 + 2 7 O 2 ! 1

besteht aus zwei nahe gleich hellen Sternen voa der Grofie etwa 9.4 in 2' Distanz, deren Positionen ich am gleichen Tage durch Anschlufi an Cantbr. 52j8 = +26"2057 ( R A . + I ~ korr.) fur 1855.0 wie folgt bestimmt habe:

I Die Originalbeobachtungen #r BD., aus denen der vorstehende Ort von + 2 7O1861 nichl; ganz richtig hergeleitet ist, lauten:

sz. 838 9?5 1OhSm32F2 f 2 7 O l:4 SZ. 852 9.3 10 5 37.3 + q 7 0.6 SZ. 874 9.5 10 5 40.4 +26 5 8 9 .

Die einzelnen Koordinaten stimmen, wia man sieht, bald mit der einen, bald mit der anderen Kompoqpnte liberein; die Sterne sind mit der 9 maligen Vergrokrung des Suchers nicht deutlich getxennt geseheo. Urn Irrungen in Zukunft zu vermeiden, empfiehlt es sich, beide Sterne gem@ der ge- nauen Bestimmung einzureihen, und also in BD. av lesen:

+26"2059a 9m4 1 0 ~ 5 ~ 3 2 1 6 +26O 59:5 +27O1861 9.4 10 5 37.4 + 2 7 1 . 4 .

Bonn, 1907 Marz 7. F. Kiistner.

Two variables discovered by M. Baillaud. ( H a r v a r d C o l l e g e O b s e r v a t o r y C i r c u l a r No. 126).

In the Comptes Rendus, 144.250, M. Jules Baillaud announces the discovery of two new variable stars whose changes in light are so rapid, that they are well shown on the plates of the Paris Observatory, having three successive exposures at intervals of half an hour. These stars are so faint that, as stated in Circular 123 (A. N. 174 .99)~ it is not pro- bable that many photographic images of them exist. I t will now be easy to determine the light curves and approximate periods of these stars by taking series of photographs at short intervals. The precise periods can then be determined with great accuracy from early photographs, especially if they were taken at a time when the light was changing rapidly. To make these observations. of value, we must known the exact time of the centre of the exposure, and the brightness of the variable compared with that of adjacent stars, so that all the observations can be reduced to a standard.scale. An examination by Mrs. Fleming of the plates in the Harvard collection led to the results given below.

The position of the first star, 3.1907 Herculis, is in RA. 16~54m2, Decl. + 2 i 0 4 2 ' (1900). The position of the second star 4 . I 90 7 Vulpeculae, according to M. Baillaud, is in RA. 1 9 ~ 0 ~ 8 5 4 4 , Decl. +24O40' 15'!8 (1900). It would therefore precede +24'3624, 3616, south 5' 41". No star appears in this position on the Paris chart, Zone +24O, No. 144. A star which precedes +24O3624, 1gS, south 8!6, is variable, and has been assumed to be the object. *) It has a fainter star which precedes it oS9, south 14". These two stars are not separated on some of the plates taken with the &inch telescope, and the combined light is estimated.

In order that the magnitudes here found for the variables may be compared with those of later photographs, six stars have been selected near the first variable and magnitudes

assigned to them arbitrarily. An attempt was made to con- form to the scale of M. Baillaud as nearly as possible. The magnitudes and coordinates of these stars, referred to the variable as an origin, are given in the first three columns of Table I. The magnitudes and coordinates of four com- parison stars of the second variable are given in the next three columns of the same table.

T a b l e I. C o m p a r i s o n s ta rs .

Magn. 1 x 1 Y 1 Xlagn. ~ x

3 , I 90 7 Herculis. 2 5 . I 90 7 Vulpeculae.

14.0

14.5 The first portion of Table I1

variable, the designation of the plate Day and decimal following Greenwic

- I 65" -354 - 48 - 24

ontains, the dat Mean j

-310" - 3 0 - 1 3 2 - 42

for the first , the Julian oon of the

middle of the exposure, the duration of the exposure, and the estimated magnitude. Photographs taken with the 24-inch Bruce Telescope are indicated by the letter A, those taken with the 8-inch Draper Telescope, by the letter I. Plate [ 18953 is an isochromatic plate. When the variable is not seen on the plate, the magnitude of the faintest star shown is given in brackets. Thus, at the time the second plate was taken, the variable must have been fainter than mag- nitude 13 .7 , since stars of that magnitude appear on the plate. The observations of the second variable are given in the same form in the second part of Table IT.

*) Beide Sterne sind nicht identisch; vergleiche den nachfolgenden Artikel von Herrn Baillaud. Der neue Pickeringsche VaFiabIe 1 9 ~ 0 ~ 2 6 ' + 2 4 O 37:3 (1900.0) wird rnit 25 .'go7 Vulpeculae bezeichnet werden. KY.

25 3

2674,567 2904.875 2963.766 4185.549 4189.543 4387.873 4470.628 4883.584 5544.749 5563.607

4168

16" 10

1 2

I 3

11

10

60 I 7

1 0

12

254

Tahle 33. 0 bse r va t i on s of uar ia b 1 es.

Plate ! Date 1 Julian Day ~ Exp. ~ Est.

I 8981

111100

I18874

I20661

A 391

118953

A 3146 123345

A 5337 1 2 7 I44

A 5482 130529 134336

3 . I 90 7 Herculis. 1893 July 29 1894 Mar. 16

2 May 14 1897 Sept. 17

1898 Apr. 7 > June 29

1899 Aug. 16 1901 June 8

> 2 2 7

I July 2 5 1903 May 2 0

1906 Nov. 8

> 2 2 I

14.2

1 2 . 7

14.2

I 4.8 13.2 14.8

(13.7)

(13.0)

(13.0)

(13.0) '4.7

. -.

It will be noticed that several plates in these tables show stars estimated as of the fourteenth magnitude or fainter, although taken with a telescope having an aperture of only 8 inches, and an exposure of ten minutes. It is stated in

Plate 1 Date 1 Juiian Day 1 Exp. I Est.

I 8951 A 779 I11647

I16090 I16380 X 2681 A 3211 A 3212 A 3214 I 2 1 2 6 1

A 5558 127433 130763 133738 134139

A '937

A 7881

25.1907 VI 1893 July 2 7 I894 Aug. I I

> Oct. I 5

x Oct. 3 1896 July 2 0

)) B 28 1897 Aug. 31 1898 Aug. 5

, " 5 " a 5 P Sept. 2 8

1901 Aug. 2 1

2 Sept. 6

1905 Dec. 8 1906 July 14

I903 .lug. 24

n > 2 1

m l a e . 2 6 7 2.649 3052.564 3 I 17.505 3761.612 3836.5 50 3861.502 4168.531 4507.609 4507.620 4507.652 4561.558 56 18.5 7 5 5634.566 6351.657 7 I 88.44 I 7406.72 I 7413.662

10" I0 I 0 I 1

I 0

I 4 75 I 0

I 0 I 0 I 0

60 35 16 26

60 2 0

'4.3 13.7

14.1 I 3.8 I 3.0 I 3.8

L3.8

13.7 13.1 14.2 14.0

I 4 .0 ' 3.7 13.9 1 4 . 2 I 4.0 13.7

Circular 123 (A. N. 174.99), that such plates seldom show stars much fainter than the thirteenth magnitude on the Harvard scale. It is therefore probable that the scale of M. Baillaud differs systematically from that in use here.

Harvard College Observatory, Cambridge, Mass., 1907 Febr. 2 5. Edward C. Pickeyiag.

L'e'toile variable 4.1907 Vulpeculae. L'etoile 4.1907 Vulpeculae que Mrs. Fleming n'a pas

pu trouver sur les plaques d'Harvard, A cause de la position erronCe que je h i avais attribuCe, a pour coordonnCes polaires

AR. = 1 9 ~ 0 ~ 8 5 2 DCcl. = +24O38'20" (1900)

e t pour coordonnCes rectangulaires

Carte 143 Zone +24O x = +56.8 y = +38.8

(L'unitC Ctant le cinqui6me de I'intervalle de deux traits du rkseau, z mm sur l'agrandissement sur papier.)

Sur la carte 143 1'6toile n'est represent6e que par ses deux images les plus intenses; sur la carte 144 les 3 points sont visibles, mais ils sont tres faibles. On peut voir aussi

2 I44 > +24' X = -53.0 J' = +38.8.

dans le m&me carrC du rCseau de cette carte les 3 Ctoiles auxquelles je fais allusion dans ma note aux Comptes Ren- dus 144 p. 250.

L'Ctoile variable 2 5 , I 90 7 Vulpeculae qu'a dkcouverte Mrs. Fleming (Harvard College Observatory, circulaire I 26) a pour coordonnCes rectangulaires

sur la carte 143 x = +60.8 y = t 3 7 . 9

Elle est de plus d'une grandeur et demie plus brillante que la precedente. Les nombres qui dans la circulaire 126 ex- priment la grandeur de celle Ctoile s'ecartent donc de notre Cchelle dam le mCme sens que de I'Cchelle ordinaire de M. Pickering.

> n )) 144 x = -49 .0 y = +37.9.

Observatoire de Paris, 1907 Mars 29. Jules BailZaud.

Berichtigung zum Generalregister der, Bande 121 bis 150 der A. N. In den A. N. 135 p. 431 und 140 p. 361 sind Beobachtungen eines Studenten Ivanow in Kasan betr. die Sonnen-

finsternis I 894 April 5, Verfinsterungen der Jupiterstrabanten und Sternbedeckungen mitgeteilt worden, die wir im General- register der Bande 1 2 1 bis 150 p. 56 irrtiimlich Herrn A. Iwanow in St. Petersburg, fruher Adjunkt der Sternwarte in Pulkowa, zugeschrieben haben. Es ist erst kiirzlich zu meiner Kenntnis gekommen, dafi beide Herren miteinander 'nicht identisch sind.

Kiel, 1907 April 2 . N; Kreuf. .