2 Observations

2.1 Optical images

The observations presented here were performed with the 0.3 m, f/3.2 wide field telescope at Skinakas Observatory on July 28, 29, and 30, 2000. A $1024 \times 1024$ Site CCD was used to image the field of interest, at an image scale of 5 $^{\prime\prime}$ per pixel, in conjunction with interference filters isolating the emission lines of H$\alpha$ and [N II], H$\beta$, [S II], [O II] and [O III]. The major characteristics of the filters can be found in Mavromatakis et al. (2001). The number of frames taken in each filter and the total exposure time are given in Table 1. The final images in each filter are the average of the individual frames. All coordinates quoted in this work refer to epoch 2000.

Standard IRAF and MIDAS routines were used for the reduction of the data. Individual frames were bias subtracted and flat-field corrected using well exposed twilight flat-fields. The spectrophotometric standard stars HR 5501, HR 7596, HR 7950, HR 8634, HR 9087 and HR 718 were used for flux calibration.

   

Table 1: Log of the exposure times.

		Images
H$\alpha +[$N II]	[S II]	[O III]	H$\beta$	[O II]
4200$^{\rm a}$(2)$^{\rm b}$	4200 (2)	10200 (5)	10200 (5)	4800 (2)
		Spectra
area I	area II	area III	area IV
7200 (2)	7200 (2)	3600 (2)	5400 (2)

${\rm ^a}$ Total exposure times in s.
${\rm ^b}$ Number of individual frames.

   

Table 2: Typical fluxes from imagery.

	area I	area II	area III	area IV
H$\alpha +[$N II]	43	64	114	75
[S II]	11	4	36	20
H$\beta$	2.6	11	16	8
[O III]	1.6	16	19	4
[O II]	22	33	96	37

Fluxes in units of 10^-17 erg s^-1 cm^-2 arcsec^-2.

   

Table 3: Coordinates of slit centers.

	area I	area II	area III	area IV
$\alpha$$^{\rm a}$	19$^{\rm h}$56$^{\rm m}$46$^{\rm s}$	19$^{\rm h}$59$^{\rm m}$30$^{\rm s}$.4	20$^{\rm h}$00$^{\rm m}$58$^{\rm s}$.2	20$^{\rm h}$00$^{\rm m}$24$^{\rm s}$.6
$\delta$$^{\rm a}$	33$^\circ$57$^\prime$15 $^{\prime\prime}$	33$^\circ$26$^\prime$59 $^{\prime\prime}$	33$^\circ$54$^\prime$34 $^{\prime\prime}$	33$^\circ$52$^\prime$21 $^{\prime\prime}$

${\rm ^a}$ Equatorial coordinates for epoch 2000.

2.2 Optical spectra

Long-slit spectra were obtained on August 02 and 03, 2000 using the 1.3 m Ritchey-Cretien telescope at Skinakas Observatory. The spectrophotometric standard stars HR 718, HR 5501, HR 9087, and HR 7596 were used for absolute flux calibration. The data were taken with a 1300 line mm^-1 grating and a $800 \times 2000$ Site CCD having a 15 $\mu$m pixel size and cover the range of 4750 Å-6815 Å. The slit had a width of 7 $.\!\!^{\prime\prime}$7 and, in all cases, was oriented in the north-south direction. The number of available spectra from each filamentary structure, and the exposure time of each spectrum are given in Table 1. Standard IRAF routines were employed for the preparation and reduction of the long-slit spectra.

Figure 2: The neighbourhood around the candidate remnant in the [O III] filter. The image has been smoothed to suppress the residuals from the imperfect continuum subtraction, while the shadings run linearly from 0.0 to 20 $\times$ 10-17 erg s-1 cm-2 arcsec-2. Emission from areas I and Ia is barely seen in the west and in the north, respectively, but is definitely detected.