This webpage is kept for archival purposes only and is no longer updated or maintained.
Posted by Bruce Balick on May 11, 1999 at 15:06:26:
As the WFC3-SOC discussions of filters broadened, I conducted a very
quick poll of EXTREMELY limited validity to see whether the selection
of any narrowband filters was going to be easy. The results are
shown in the table below.
The ultimate selection of filters will NOT be affected by this poll.
Rather, the selection of filters will be a completely open and
uniform process, and all input must be submitted using formal
established procedures.
I'm posting this poll just to excite, enrage, and provoke everyone into
taking the time to provide even better advice in the filter selection
process. This message is NOT a call for more input to me.
--Bruce Balick
--------------------------------------------------------------
THE POLL...
I polled six members of the narrowband community in order to solicit
their sense of priority for important emission lines and their
associated filters. These are people who have used WFPC2 for studies
of YSOs, H-H objects, HII regions, planetaries, novae, and supernovae.
No representatives of the solar system or extragalactic communities
were included.
Each respondent was given a brief summary of the narrowband imaging
capabilities of WFPC2, STIS, and ACS as well as the expected
performance of WFC3.
The poll has almost no statistical validity; nonetheless the results
seem plausible. In short, the dozen narrowband filters on WFPC2 were
all big hits -- in spite of the fact that some of them are available
on STIS and ACS. Another big hit was a filter for [NII]5755A.
Please note that no one was asked to identify critical off-band
continuum filters (though some did anyway). Such filters are important
for faint lines which also transmit signficiant amounts of continuum.
This issue is wide open.
Priorites are
1 = must have
2 = very important
3 = useful but not essential if filter space is limited
The number of narrowband slots on WFC3 is likely to be in the range
of 20-24, though this is certainly only a guess and will need to
be discusssed and justified. Accordingly, each respondent was asked
to select 10 prio-1 filters, 10 prio-2 filters, and 4 prio-3 filters.
Please note that not all of the respondents follow instructions
particularly well...which includes me, I'm afraid!
THE RESULTS...
WFC3 will have a uv-visible channel between about 200 and 1000 nm and
a separate IR channel from about 800 to 1800 nm. The performance and
wavelength limits of both channels are still under study. Accordingly,
the C III]1909A and Paschen-alpha 18751A filters should be considered.
"risky". Any decision to use them will have to await future performance
studies.
UV-vis narroband filters
Priority lambda filter line & comments
---------------------------------------------
OMWBHB - initial of respondent
------
33 1 1909 F191N CIII] - reject SiIII]1885 if possible
2 2326 F233N CII], - reject SiII]2335 if possible
2 2425 F243N [NeIV],
11 1 2798 F280N MgII,
1 3078-3099 F309N OH(0,0) series
221 *3426 F343N [NeV],
11211 *3726+3729 F373N [OII] 3727 - nearby faint contaminating lines
F375N [OII] redshifted - perhaps covered by medium filter?
122 *3869 F387N [NeIII] - must reject H-epsilon and HeI lines
F390N CN ??, from WFPC2 ,
F390N off CaII - perhaps covered by medium filter?
3945 F393N CaII,
2 2 4340 F434N H-gamma
22121 *4363 F437N [OIII] (must reject H-gamma)
- must be used wit F502N
2 4471 F447N HeI
2 4572 F457N [Mg I]
11111 *4686 F469N HeII,
4740 F474N [NeIV] (I added this to your list)
121111 *4861 F487N H-beta,
1 1111 *5007 F502N [OIII],
2 5199 F520N [NI]5198+5200
2 5303 F530N [Fe XIV],
5517 F552N [Chlorine III] - must be used with but reject 5537
5537 F554N [Chlorine III] - must be used with but reject 5517
3 5577 F558N [OI] - must be used with 6300
- 6300 must reject 6312
22 12 5755 F575N [NII] - must be used with F658N
1121 *5876+5892 F588N HeI/NaI,
111111 *6300 F631N [OI],
112111 *6563 F656N H-alpha,
1 1112 *6584 F658N [NII],
2 6678 F668N HeI
111112 *6717+6731 F673N [SII],
2 1 6717 F673AN [SII] - must be used with but reject 6731
2 1 6731 F673BN [SII] - must be used with but reject 6717
22 7005 F701N [ArV],
1 2 7135 F714N [ArIII],
3 11 7319-7331 F733N [OII] four auroral lines 7319,21,29,31
2 2 7387 F739N [NiII],
2 7412 F741N [NiII],
F750N [NiII off] - perhaps covered by medium filter?
3 3 8617 F862N [FeII],
13312 *9532 F953N [SIII],
22 1 9850 F985N [CI]
1 Methane quad (543N, 619N, 727N, 893N),
2 1 UV Narrow quad (376N, 384N, 392N, 399N)
3 F663N continuum between [NII]6584 and HeI6678
Here is an unprioritized list of possible IR narrowbands.
What's missing?
10320 F1032N [SII] - sum of [SII] 10284, 10317, 10336, 10370
probes S+ in very dusty regions;
measure extinction with [SII]4076 (common
upper level)
10830 F1083N HeI
12400 F1240N H_2 12260+12327+12380+12416+12418+12470
mini forest of medium bright H_2 lines
- must reject [FeII]12567
12818 F1282N Paschen-beta - not necessary of P-alpha is included
12567 F1257N FeII line; same upper state as 1.644 micron line
Good for extinction and for HH objects.
16436 F1644N [FeII] Traces high density shocks at modest
velocities
Excellent tracer of inner jets in embedded
YSOs. We (Reipurth, Bally) have used this
line to trace jets with NICMOS.
17470 F1748N H2 1-0 S(7)
Note: This is only an approximate
wavelength.
Need to investigate other possible H2 lines
in the H band.
18751 F1875N Paschen-alpha - use to probe H+ in
very dusty regions
and to measure extinction with H-gamma
(common upper level)
Follow Ups:
- Curator: J.D. Myers
- NASA Official: Phil Newman
- Science Official: Kenneth Carpenter
- › Privacy Policy and Important Notices
- › Contact NASA
- › Fermi FAQ, Comments, Feedback
- › Page Last Updated: Tue, Feb 07, 2012