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Astron. Astrophys. 338, 977-987 (1998)

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2. Observations and results

The observations presented here have been collected as part of the DENIS survey between January and May 1996 at La Silla (Chile) using the ESO 1 metre telescope equipped with the specially designed 3-channel camera (Epchtein, 1997; Copet et al., 1998). They cover an area of [FORMULA] centred at [FORMULA] (J2000) in three bands, namely I (0.8[FORMULA]), J (1.25[FORMULA]) and [FORMULA] (2.15[FORMULA]). They consist of 13 strips each involving 180 images of [FORMULA] taken at constant RA along an arc of [FORMULA] in declination. The overlap between two adjacent strips reaches [FORMULA] in the Cha I cloud because of the proximity of the south pole. Wherever a star is picked up in two adjacent strips, position and flux values are averaged. Limiting magnitudes are 18, 16 and 13.5 at [FORMULA] in I, J and [FORMULA] bands, respectively, and a conservative estimate of the position accuracy is [FORMULA] rms in both directions. The numbers of stars detected in [FORMULA] are [FORMULA], [FORMULA] and [FORMULA], respectively. Table 1 displays a list of known stars associated with the Cha I cloud with the DENIS positions and [FORMULA] photometry. Names given in column 4 refer to previous investigations quoted in the footnote 1 of the table. Column 9 lists the cloud extinction as measured on our map (Cambresy et al., 1997), and col. 10 the extinction derived from the [FORMULA] colour excess. Table 2 presents the list of our new candidates, their DENIS positions and photometry, and the extinction derived in the same way as in Table 1.


[TABLE]

Table 1. List of known T Tauri stars



[TABLE]

Table 1. (continued)



[TABLE]

Table 1. (continued)
Notes:
1) T# from Schwartz (1991) ; Sz# from Schwartz (1977) ; C# from Hyland et al. (1982), Jones et al. (1985) ; CHX# from Feigelson & Kriss (1989) ; CHXR# from Feigelson et al. (1993), Lawson et al. (1996) ; Baud# from Baud et al. (1984) ; Hn# from Hartigan (1993) ; B# from Alcalá PhD thesis, referenced in Lawson et al. (1996) ; Ced110 IRS# from Prusti et al. (1991)
2) Out of field.
3) Not detected in J nor in [FORMULA], I not available.
4) I not available.
5) I not available.
6) Not detected in [FORMULA].
7) Not detected by DENIS. Previous measurement (Prusti et al., 1992) have found [FORMULA] and [FORMULA]. Since the detection limit is 16 in J this object should have important luminosity variation.
8) Not detected by DENIS. Previous measurement (Hyland et al., 1982) have found [FORMULA] and [FORMULA]. This object is in the line of sight of the Infrared Nebula (IRN).
9) Not Detected. Measured by Hartigan (1993), [FORMULA] [FORMULA].
10) Not Detected. Measured by Hartigan (1993), [FORMULA] [FORMULA].



[TABLE]

Table 2. Position and DENIS colours of new YSO candidates


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© European Southern Observatory (ESO) 1998

Online publication: September 17, 1998
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