...USA
1

...(FNRS)
2

...Canada
1

...21218
1

...5-26555.
2

...Fellow.
3

...Fellow.
4

...Investigator.
5

...with
The optical passbands are on an ``AB''--normalized system, whereas the K magnitudes are the standard system. A flat spectrum (1299#1299) source has 1300#1300

...M,
The parameters of the IMF are relevant for extrapolating the observed rate of formation of massive and short-lived stars to the total SFR; for our purposes the slope of the IMF is the important parameter, while the upper mass cut-off has only a minor effect---see Table 2 of Leitherer et al. 1995.

...Japan
1

...Fellow
2

...Dobrzycki
1

...USA
2

...USA
1

...Germany
1

...Observatory
2

...archive
3

...89154
1

...STScI.
2

...Italy
1

...Germany
1

...U.S.A
1

...94720-3411
1

...Italy
1

...Italy
2

...IZw18
1

...White
1

...Sweden
2

...Sweden
3

...USA
4

...USA
5

...Germany
6

...USA
7

...USA
8

...USA
9

...diagnostic.
There is NV3123#3123 and NIV3124#3124. However, NIV3125#3125 is a dielectronic recombination line and therefore, it is sensitive to the N3126#3126 population as is the NV3127#3127 line.

...Israel
1

...Canada
2

...USA
1

...shown
Data sets number 1 and 4 exhibit much higher noise possibly due to higher HST jitter and are, therefore, not included in the analysis.

...amplify
A different analysis of HST data is described in the article Are the Pulses of Crab Pulsar Modulated? (to appear in A&A).

...is
A similar peak appears at the channel number 405, corresponding to frequency 3656#3656. We have no possibility to observe at this frequency in Asiago, so that we do not wish to speculate on its significance.

...France
1

...Paresce
1

...France
2

...USA
3

...Russia
4

...Germany
5

...acauleteso.org
1

...Chile
1

...Germany
1

...France
2

...USA
1

...France
2

...France
1

payne@stsci.edu