Each Astro-E2 proposals must include at a minimum the source coordinates, exposure time, instrument configuration and expected count rates, and any observing constraints within the four page limit. The review panels will base their decision primarily upon the justification of the proposed science to be done with the data. This chapter describes how to prepare a strong proposal, including the various software tools available to assist the proposer.
While it is conceivable that one would wish to study a previously unknown X-ray source with the XRS, a more likely scenario would involve a detailed spectroscopy of an object with known X-ray flux. A viable proposal should state the scientific objective as to what new information will be gleaned from the high resolution spectrum. Of crucial importance is the justification for the requested exposure time, especially given the limited lifetime of the XRS. This will likely require at least a simulation of the expected spectrum, or possibly a simulation of the entire observation.
Every Astro-E2 proposal must have an estimate of the expected counting rates from the proposed target. This rate is used both by the reviewers to evaluate the viability of the proposal and the operations team to evaluate any safety concerns. The simplest tool to use in estimating the expected XRS or XIS count rate is PIMMS. This tool is freely available as a stand-alone tool or on the Web as WebPIMMS; see Appendix C for locations. The next level of detail is provided via simulations using XSPEC, and such simulations should provide significant insight into the expected spectrum obtained from a proposed observation. A brief guide to XSPEC simulations is given in § 4.3. In many case, this should be sufficient for a point source. There are also tools available to simulate imaging data, which may be useful for an extended source or a particularly bright source. In particular, the most powerful tool is xrssim, which can use a FITS format image with an assumed spectral shape of the source to estimate the distribution of events in all elements of the XRS array.
This tool is an interactive, menu-driven program, which has an extensive HELP facility. It is also available as the web-based tool WebPIMMS. In either case, users specify the flux and spectral model with its parameters, and PIMMS/WebPIMMS returns the predicted counting rate. PIMMS/WebPIMMS can be used for a variety of other instruments, so if for instance the counting rate and spectrum of a given source observed with the ROSAT PSPC is known, it can calculate the flux, which in turn can be used as input to estimate the XRS counting rate.
Perhaps the easiest tool for simulating X-ray spectra is the XSPEC
program (a part of the XANADU software package), which is designed to
run on a variety of computer platforms and operating systems and is
freely distributed on the NASA GSFC HEASARC Website (see
Appendix C). The simulation of an XRS observation
requires the current instrument redistribution matrix (the so-called
.rmf file) and the energy-dependent effective area of the instrument
(the so-called .arf file), both available on the Web or via anonymous
FTP (see Appendix C). For the purpose of the simulation,
these files assume that all pixels can be described by a single
matrix, and that the source of photons is a point source. Although
the on-orbit performance of the XRT-S is unknown, the point source
.arf file assumes that 64% of the photons from an on-axis point
source will reach the XRS array, based on a conservative estimate
(
) of the XRT-S HPD. For a constant diffuse source that fills
the field of view, the XRS array will be more uniformly illuminated
and the effective area (and thus count rate) will be slightly larger
(
), although the exact value depends on the surface
brightness and spectrum of the source. The best estimate of the XRS
effective area for a diffuse source can be calculated using xrssim (described below).
The procedure for simulations is relatively simple: if the XSPEC program is installed, one should start XSPEC making sure that the proper .rmf and .arf files are accessible. Within XSPEC, one should specify the spectral model, such as hot thermal plasma or the like (via model command). Specifying the model will drive XSPEC to query for the model parameters (such as temperature and abundances for an APEC collisional plasma model), as well as normalization. The key command to create a simulated spectrum is the fakeit command, which will query for the redistribution response (the .rmf file), and the ancillary response (the .arf file). The fakeit command also will request the simulated data filename, and the length of simulated observation. One can now use this file within XSPEC to determine the sensitivity of the simulated data file to changes in the model parameters.
Most of the features of XSPEC are also available as a web-based tool on the HEASARC website (see Appendix C). WebSPEC calls XSPEC behind the scenes, so all the issues described above apply here as well. WebSPEC contains the effective area and response files for Astro-E2 already, and allows the proposer to simply select which filters will be used. The fact that the XRS array does not sample the entire beam is also taken into account in the effective area.
After selecting the instrument, WebSPEC allows the user to choose the spectral model, such as an absorbed collisional plasma or a power-law spectrum with an absorption component. The next page will then query for the model parameters (such as temperature and abundances for an APEC collisional plasma model), as well as normalization, exposure, upper and lower energies, and the number of bins to use in the spectral plot. WebSPEC will then create a simulated spectrum after clicking the ``Show me the Spectrum'' button, using the fakeit command. This folds the specified model through the instrument response and effective area, calculating the observed count rate and fluxes as well. WebSPEC will then allow one to download the postscript file of the spectrum, change the model parameters, or replot the data.
To show how to estimate the proper exposure, we include some simple examples of XRS observations that illustrate the process.
line at
keV). Assume that the continuum flux at 6.4 keV
is
photons cm
s
keV (a good
approximation for an AGN with a 2 - 10 keV flux of 
erg cm s), while the line flux is
photons cm s. Assume also that the line is
unresolved with an ASCA observation, such that 
eV. We
can also assume that the level of continuum is known precisely, from
simultaneous observations with the XISs.
To take advantage of the energy resolution of the calorimeter in
measuring the structure of the line, one should have a meaningful
measurement of the line flux in each 10 eV energy bin to, say, 20% or
better. The effective area of the XRS + XRT at 6.4 keV is 
cm
. A crude, order-of-magnitude estimate can be made as
follows:
The continuum flux in the vicinity of 6.4 keV is
photons cm s per 10 eV bin. Let us assume
for the moment that the the line flux is uniformly distributed over
100 eV, or ten 10 eV-wide bins. This means that each 10 eV bin will
have 
line photons cm s. Total is
photons cm s per 10 eV bin. If one wishes to
measure the structure of the line such that the flux of the line in each energy bin is known to 20%, we require the total of 75
line photons per bin (one must consider the Poisson statistics of both
line and continuum photons). This now translates to an exposure of
s, or 
ksec. For an isolated
line (with no continuum), a similar argument would suggest an
observation of
s, or 
ksec.
Consider a project to measure the abundance of iron in a cluster of
galaxies using the He-like and H-like Fe K lines, such that the 90%
confidence regions are 
Solar. (In the case of such a hot
cluster, most of temperature / abundance information comes from the Fe
K rather than Fe L region.) The ROSAT PSPC and ASCA observations
indicate that the intervening absorption is small (
cm), the spectrum is well-described by an APEC collisional
plasma model with a temperature 
of 6 keV and abundances of 
Solar, and that the cluster image is circular, with a diameter
of 10
. Those data also show that the 0.2 - 2 keV flux from the
whole cluster is
erg cm s, and the
surface brightness is reasonably uniform.
An important issue to keep in mind is the surface brightness of the
cluster, which affects the results in two ways. First, the XRS
subtends only 
arcmin on the sky, while the entire
cluster subtends 
arcmin. This means that the 0.2 - 2
keV flux in the XRS beam is only 1/10th of the total, or
erg cm s. Secondly, since the cluster will
fill the XRS field of view, the final count rate might be somewhat
conservative since the .arf file assumes the source is a point source.
We begin by simulating the spectrum with XSPEC using a nominal time of 100 ksec, using an absorbed APEC collisional plasma model with a normalization (0.000783) which gives the desired flux between 0.2-2.0 keV:
XSPEC> model wabs*apec
Model: wabs<1>( apec<2> )
Input parameter value, delta, min, bot, top, and max values for ...
1:wabs:nH>0.02
2:apec:kT>6.0
3:apec:Abundanc>0.3
4:apec:Redshift>
5:apec:norm>0.000783
XSPEC> fakeit none
For fake data, file # 1 needs response file: xrs_2d6eV_2003-02-19.rmf
... and ancillary response file: xrs_onaxis_all_2003-09-30.arf
Use counting statistics in creating fake data? (y)
Input optional fake file prefix (max 4 chars):
Fake data filename (xrs_2d6eV_2003-02-19.fak) [/ to use default]: cluster.fak
Exposure time, correction norm (1, 1): 100000
XSPEC> flux 0.2 2.0
Model flux 4.0046E-04 photons ( 5.0114E-13 ergs)cm**-2 s**-1 ( 0.200- 2.000)
We have now created a sample ``fake'' dataset called cluster.fak with the correct flux. To consider only the Fe K lines, we restrict the fit to the 4-10 keV band, where the only strong emission lines are from Fe K. We fit the data using an absorbed APEC model to determine the accuracy to which we can measure the abundance. Note that we have to thaw the model abundance (which is by default fixed), and use the cstat statistical model since we have very few counts per bin.
XSPEC> freeze 1
XSPEC> thaw 3
XSPEC> statistic cstat
XSPEC> ignore **-4.0, 10.-**
XSPEC> fit
XSPEC> error 2.706 3
Parameter Confidence Range ( 2.706)
3 0.266950 0.530534 ( -0.113708 , 0.149875 )
This shows that the total 90% confidence range is 
,
slightly larger than the desired value of . However, the
source is diffuse and fills the field of view, so the observed count
rate might be as much as 50% larger. The potential effect can be
quickly estimated by redoing the simulation using a time of 150 ksec
and refitting, which leads to a 90% confidence range of
. Therefore, 100 ksec should suffice for this science;
to get a more accurate estimate, xrssim could be used to
simulate the entire observation and get the true count rate.
Suppose we have a collisional plasma source and we want to determine any internal velocity spread in excess of that due to the temperature. V11.3.1 of XSPEC includes two new models, bapec and bvapec, which apply thermal and gaussian velocity broadening to emission lines. The sigma of the gaussian velocity broadening (in km/s) is a parameter of these models. We can use these models to ``fake'' a 100 ksec observation and then determine how small a velocity broadening we could detect at the 90% confidence level.
XSPEC>model phabs(bapec)
Model: phabs<1>( bapec<2> )
Input parameter value, delta, min, bot, top, and max values for ...
1:phabs:nH>0.1
2:bapec:kT>4
3:bapec:Abundanc>0.3
4:bapec:Redshift>0.05
5:bapec:Velocity>200
6:bapec:norm>
...
XSPEC>thaw 3
Number of variable fit parameters = 4
XSPEC>new 6 1e-2
XSPEC>ignore 0.-0.5 10.-**
ignoring channels 1 - 501 in dataset 1
ignoring channels 10000 - 16384 in dataset 1
XSPEC>fakeit none
For fake data, file # 1 needs response file: xrs_2d6eV_2003-02-19.rmf
... and ancillary response file: xrs_onaxis_all_2003-09-30.arf
Use randomization in creating fake data? (y)
Input optional fake file prefix (max 4 chars):
Fake data filename (xrs_2d6eV_2003-02-19.fak) [/ to use default]: test.fak
Exposure time, correction norm (1, 1): 100000
Net count rate (cts/s) for file 1 0.4233 +/- 2.0575E-03
using response (RMF) file... xrs_2d6eV_2003-02-19.rmf
using auxiliary (ARF) file... xrs_onaxis_all_2003-09-30.arf
Chi-Squared = 7513.420 using 9498 PHA bins.
Reduced chi-squared = 0.7913862 for 9494 degrees of freedom
Null hypothesis probability = 1.00
XSPEC>stat cstat
C-statistic = 8794.805 using 9498 PHA bins.
XSPEC>fit
---------------------------------------------------------------------------
Model: phabs<1>( bapec<2> )
Model Fit Model Component Parameter Unit Value
par par comp
1 1 1 phabs nH 10^22 0.100616 +/- 0.336496E-02
2 2 2 bapec kT keV 3.92762 +/- 0.493891E-01
3 3 2 bapec Abundanc 0.305391 +/- 0.129515E-01
4 4 2 bapec Redshift 5.000000E-02 frozen
5 5 2 bapec Velocity km/s 200.000 frozen
6 6 2 bapec norm 1.007288E-02 +/- 0.105322E-03
---------------------------------------------------------------------------
We have now created a fake 100 ksec observation using an absorbed apec model that includes a 200 km/s velocity broadening to all lines, and then fit it while fixing the velocity broadening and redshift. We now allow the velocity term to vary and have XSPEC calculate the 90% confidence interval around the best-fit value:
XSPEC>thaw 5
XSPEC>fit
---------------------------------------------------------------------------
Model: phabs<1>( bapec<2> )
Model Fit Model Component Parameter Unit Value
par par comp
1 1 1 phabs nH 10^22 0.100600 +/- 0.336504E-02
2 2 2 bapec kT keV 3.92907 +/- 0.494203E-01
3 3 2 bapec Abundanc 0.303315 +/- 0.129845E-01
4 4 2 bapec Redshift 5.000000E-02 frozen
5 5 2 bapec Velocity km/s 167.628 +/- 23.4625
6 6 2 bapec norm 1.007846E-02 +/- 0.105433E-03
---------------------------------------------------------------------------
---------------------------------------------------------------------------
XSPEC>unc 5
Parameter Confidence Range ( 2.706)
5 132.119 205.914 ( -35.5092 , 38.2857 )
So a 100 ksec observation could easily detect the intrinsic 200 km/s velocity broadening of this plasma, with the 90% confidence interval ranging from 132-205 km/s.
xrssim is an Astro-E2 XRS event simulator. It reads a FITS format photon list file, traces photon paths in the telescope (via ray-tracing), and outputs a simulated XRS event file. XRT thermal shield transmission, XRS filter wheel transmission, and XRS detection efficiency are taken into account if requested. Each record of the photon list file describes the celestial positions, arrival time, and energy of the input photon. The mkphlist ftool can create such photon list files from FITS images (e.g., ROSAT HRI images) and spectral models (which may be created in XSPEC). The xrssim output event file may be analyzed just like a real data, using standard analysis tools such as xselect.
When planning XRS observations, there will be at least two situations where xrssim will be useful:
These programs are available from the Tools web page listed in Appendix C.
We consider here an observation of GX13+1, an LMXB with Fe K lines that happens to be a SWG target. One of the goals of the observation is to resolve and measure the Fe K lines. From §2.3 we know that the fraction of high resolution events declines when the source flux becomes too high (cf. Fig 2.11), which would affect the results. This can be mitigated using either the neutral density filter or the Be filter, at the cost of substantially reducing the count rate. To properly evaluate the best filter setting requires an xrssim simulation. Fortunately, this is not difficult.
After installing the mkphlist and xrssim software, the first step is to prepare the input spectrum for mkphlist. After finding a good spectral model for the source (in this case, taken from Ueda et al. 2001, ApJ, 556, L87), we set up the model in XSPEC as follows:
XSPEC> model wabs*edge*(diskbb + bb + gauss + gauss) Model: wabs<1>*edge<2>( diskbb<3> + bbody<4> + gaussian<5> + gaussian<6> ) Input parameter value, delta, min, bot, top, and max values for ... 1:wabs:nH>2.9 2:edge:edgeE>7.61 3:edge:MaxTau>0.13 4:diskbb:Tin>0.91 5:diskbb:norm>1078.72 6:bbody:kT>1.45 7:bbody:norm>0.1224 8:gaussian:LineE>6.42 9:gaussian:Sigma>0.02 10:gaussian:norm>2.48e-3 11:gaussian:LineE>7.01 12:gaussian:Sigma>0.02 13:gaussian:norm>-3.465e-3 0.01 -1 -1 1 1 XSPEC> dummyrsp 0.1 10 3000 lin XSPEC> flux 0.1 10 Model flux 1.897 photons ( 1.1863E-08 ergs)cm**-2 s**-1 ( 0.100- 10.000) XSPEC> plot model XSPEC> iplot XSPEC> wdata spectrum.qdp
These commands define the model, show the total flux, and create an input spectrum file spectrum.qdp with energy bins 3.3 eV wide. This is adequate since only an estimate of the count rates for the different event types is needed. Finer binning might be needed for other projects, such as estimating how accurately a narrow line could be measured. Now spectrum.qdp can be used input to mkphlist to generate a list of photons to be simulated by xrssim. For this example, we run mkphlist as follows:
unix% mkphlist photon flux in photons/s/cm2 (astePhotonGen)[3.325] 1.897 Emin (keV) for photon flux (astePhotonGen)[2.0] 0.1 Emax (keV) for photon flux (astePhotonGen)[10.0] 10.0 SPEC-MODE 0:QDP-SPEC, 1:MONOCHROME (astePhotonGen)[0] 0 qdp spectral file (astePhotonGen)[crab.qdp] spectrum.qdp IMAGE-MODE 0:FITS-IMAGE, 1:POINT-LIKE (astePhotonGen)[1] 1 R.A. (deg) for point source (astePhotonGen)[83.5] 273.63 DEC (deg) for point source (astePhotonGen)[22.0] -17.157 TIME-MODE 0:CONSTANT, 1:POISSON (astePhotonGen)[1] 1 LIMIT-MODE 0:NPHOTON, 1:EXPOSURE (astePhotonGen)[1] 0 exposure time in sec (astePhotonGen)[20] 1000000 output photon FITS file (astePhotonFITSwrite)[crab.photons] gx13.photons
The meaning of these parameters is explaining in the documentation
accompanying mkphlist, but briefly, the first five set the total flux,
energy range, and spectrum tpye. mkphlist can use a FITS image
or simply assume a point source for input. The source position
(RA,Dec) is not required for this purpose, but can be used. Finally,
the events may be distributed either evenly spaced or with poisson
distribution. We use the poisson distribution, since this will affect
which photons become Hi-, Mid- or Low-res. Finally, we selected a run
with 
photons, and put the output into the file gx13.photons.
This file can now be input to xrssim, as shown here. Note that xrssim uses a number of FITS files for which the default files should be used. The exact command sequence for our example is:
unix% punlearn xrssim
unix% xrssim
teldef file for XRS (SimASTEroot)[xrs_teldef_2003-02-15.fits]
default 1st Euler Angle (deg) (SimASTEroot)[83.5] 273.63
default 2nd Euler Angle theta (deg) (SimASTEroot)[68.0] 107.157
default 3rd Euler Angle psi (deg) (SimASTEroot)[0.0]
Name of input photon file #1 (astePhotonRead)[crab.photons] gx13.photons
Name of input photon file #2 (astePhotonRead)[none]
Xray Telescope Description File name (asteXRTsim)
[xrt-s_geometry_45degrot_1999-02-19.fits]
Reflection Table file name (asteXRTsim)[xrt-s_reflect_2003-09-10.fits]
Pre-Collimator Description File name('none' means no use of collimator) (asteXRTsim)
[xrt-s_precollimator_geometry_45degrot_2003-09-11.fits]
Pre-Collimator Reflection (asteXRTsim)[xrt-s_reflect_2003-09-10.fits]
XRT thermal shield transmission file (asteXRTsim)
[xrt_thermal_shield_trans_2003-01-20.fits]
Name of input RMF file (asteXRSRMFsim)[xrs_2d6eV_2003-02-19.rmf]
XRS Filter Wheel filter transmission file (asteXRSRMFsim)[none]
Multiply XRS effciency or not (asteXRSRMFsim)[yes]
Discard events fallen outside of pixels (asteXRSRMFsim)[no]
output event FITS file (asteEventFITSwrite)[crab.events] gx13_evt.fits
The inputs for xrssim are described in the documentation, but a
short review is given here. The fields called ``teldef file for the
XRS'', ``Xray Telescope Description File'', `` Reflection Table'',
``Pre-Collimator Description File'', ``Pre-Collimator Reflection'',
``XRT thermal shield transmission'', and ``Name of input RMF file''
should be left unchanged and all the files described should be in the
current directory. The remaining options can be varied to set the
pointing direction, filters used, and the details of the simulation.
The 1st Euler Angle should be set to the RA of the source used in mkphlist. However, the Euler angle theta is defined as
minus the target Declination, so theta(xrssim) = 90
- DEC(mkphlist). The Euler Angle psi is similarly related to the
Astro-E2 Roll Angle, such that the Roll Angle 
psi. If desired,
the XRS Filter Wheel transmission file can be set to xrs_fw_pos3_be300_trans_2003-11-10.fits to use the 300
m Be
filter. The 10% neutral density filter can be approximated by simply
reducing the input flux in mkphlist by a factor of 10.
Optionally, the XRS efficiency may be included or not, and events that
do not land on a pixel may be excluded to save space.
The final result of this run is the file gx13_evt.fits and a table of pixel statistics, output at the end of the xrssim run. For this run, the table breaks the emission down by pixel, and a précis is shown here:
Pixel Total Hi-Res Mid-Res Low-Res Secondary 7 11759 5(0.04%) 1949(16.5%) 9805(83.3%) 11492(97.7%) 15 2392 553(23.1%) 1076(44.9%) 763(31.8%) 1233(51.5%) ... all 118812 13015(10.9%) 38224(32.1%) 67573(56.8%) 89462(75.2%)Out of the 118,812 events detected only 11% will be Hi-res; more than will pass the 10% neutral density filter, but possibly adding the
m filter would increase the number of Hi-res counts. However,
primary Mid-res counts have nearly the same resolution as Hi-res
counts, so we should check that first. This can be done using the
FTOOL fstatistic:
unix% fstatistic "gx13_evt.fits[EVENTS][PIXEL.ge.0 && PIXEL.ne.3 && FLAG_MIDRES.ne.0 && FLAG_SECONDARY.eq.0]"which in this case shows 10,058 matching rows with a primary (i.e., FLAG_SECONDARY is 0) Mid-res (i.e., FLAG_MIDRES is not 0) event. Adding that to the 13,015 Hi-res events shows that
of the
events will have good energy resolution. Re-running the simulation
(using the same gx13.photon file) with the 300m Be filter
file listed above returns Pixel Total Hi-Res Mid-Res Low-Res Secondary 7 5670 163(2.87%) 2207(38.9%) 3300(58.2%) 4723(83.2%) 15 1092 557(51.0%) 350(32.0%) 185(16.9%) 311(28.4%) ... all 57210 14698(25.6%) 21827(38.1%) 20685(36.1%) 31756(55.5%)So at a cost of more than half the events, we can increase the Hi-res fraction to 25.6% percent-but the actual number of counts (14,698) is only slightly more than with the OPEN filter (13,015). Re-running the fstatistic command adds an additional 7000 primary Mid-res events for a total of 21,698-fewer than the 22,902 seen with the OPEN filter. We therefore chose to use the OPEN filter, since it returns the most data.
It should also be noted that unlike CCD pile-up, there is very
little degradation of the energy resolution in Hi-res and primary
Mid-res events detected from high flux sources. CCD pileup,
especially at small or moderate levels, is difficult to detect since
the piled-up events simply appear to be from higher-energy photons.
This is not the case with the calorimeter. Even for Low-res events,
the true energy is measured; only the accuracy of the measurement is
affected. However, X-rays hitting the silicon frame outside of the
pixels and thermal crosstalk from other pixels are a source of noise
that at very high incident flux begins to degrade the XRS resolution
in the Hi-res and Mid-res grade events. For an observation of a point
source, we project that the resolution will degrade to 
eV
for source fluxes (in the Astro-E2 XRS bandpass) of 
ergs/s/cm
.
One of the first tasks in preparing a proposal is determining when and for how long a target can be observed. This can be easily done with Viewing, a simple Web-based interactive tool (see Appendix C for location) that can determine visibility for many different satellites. To use Viewing, simply enter the target name or coordinates, and select the satellite. Viewing will return all the available dates when that target will be available.
MAKI is another Web-based interactive tool (see Appendix C) that can determine the orientation of the XRS array (or the XIS) on the sky as a function of the observation epoch within the visibility window of the target. For Astro-E2, the orientation of the Solar panels with respect to the spacecraft is fixed, and at the same time, the range of the angles between the vector normal to the Solar panels and the vector pointing to the Sun is restricted, which in turn restricts the roll angle of the spacecraft.
When using the tool, general instructions are available via the ``Help'' button. section. To check the visibility and available roll angles for a target, first load an image. This can be done with either an existing FITS image, or by entering the RA and Declination of the source and clicking the ``New Graph'' button. This creates an image upon which the Astro-E2 XRS or XIS field of view (FOV) will be shown.
The ``Mission and Roll Selector'' (in the upper right of the display) allows different instruments from different missions to be selected. After selecting either the Astro-E2 XRS or XIS, a FOV will appear on your image. The FOV can be rotated using the ``Roll angle'' slider bar.
RPS, or the Remote Proposal Submission tool, must be used to enter the basic proposal data into the ISAS/JAXA, HEASARC, or ESA database. Proposers should make sure they use the correct RPS, since their are multiple reviews. See Appendix C for the list of RPS websites and addresses. Two versions of RPS are available: a character-oriented version, where the user submits all the required information via e-mail, or a Web-oriented version.
One aspect of RPS that is not immediately obvious is how to specify the time-constrained observations. For instance, a need for such an observation may arise for a study of a spectrum of a binary system in a particular orbital phase. If some particular aspect of the observation cannot be clearly specified in the RPS form, the user should detail it in the ``comments'' field of the RPS form and/or contact either the Astro-E2 team at ISAS/JAXA or the NASA Astro-E2 GOF before submitting.
A successful Astro-E2 proposal, from a technical point of view, must include the following elements:
Note that the GOs are allowed to propose for targets already approved
for the SWG time (see the Announcement of Opportunity). However, GOs
must explain why the already-approved observation does not meet their
scientific objectives. Valid reasons include a much longer exposure
time (
longer); incompatible time constraints;
different positions within an extended source.
We note also that the XISs are also subject to count rate limitations,
because of possible multiple events in an XIS pixel within one frame
(see § 7.6). This is much less of a problem than
with the ACIS aboard Chandra, as Chandra's mirror focuses the X-ray
flux into a region of a CCD that is orders of magnitude smaller. The
rule of thumb is that the XIS can tolerate a point source with a count
rate up to counts s per CCD with essentially no loss
of counts or resolution. For brighter sources, these limitations can
be reduced via a variety of XIS modes, such as the use of a sub-array
of the XIS, as discussed in § 7.5. More details
regarding which XIS mode is most appropriate for what observation will
be known after Astro-E2 is in orbit, so for borderline cases the proposer
may choose to specify the default (full-frame) mode of the XIS, and
coordinate adjustments with their contact scientist later.
There are three additional NASA-specific proposal rules that must be followed by US proposers. First, a ``Notice of Intent'' (NOI) should be submitted to the Web address listed in the official announcement (see Appendix C) by June 16, 2004. Filing a NOI will aid the NASA Astro-E2 GOF in organizing the proposal review, although proposals may be submitted without first filing an NOI. Secondly, a NASA Cover Page which includes a proposal and budget summary must be generated, using the Web form listed in §C. The cover page requires some budget information, and as noted in the official NASA announcement, a placeholder value of $1 should be used since budget information is not required until Stage 2. After submitting the cover page, a copy should be printed and saved for use in the Stage 2 budget process. Finally, as described in the NRA, the NASA Office of Space Science requires all proposals to demonstrate their relationship to NASA Goals and Research Focus Areas (RFAs). Therefore, each proposal should include a sentence stating its specific relevence to one of the RFAs given in Table 1 of the Summary of Solicitation. In particular, Astro-E2 science will often address the science themes in the ``Astronomical Search for Origins'' and the ``Structure and Evolution of the Universe.''