New Proposer Guide

Important Links

Call for Proposals (CfP)
Rules regarding Chandra proposals
Proposers' Observatory Guide (POG)
Observatory and specific instrument specifications
Remote Proposal Submission (RPS)
Software used to submit a proposal

Checking Existing Programs

Before you get too far into the process of preparing a proposal, check to see if your target has already been observed. If it has, you may want to consider an archive proposal. Or, if you don't know the target you want to observe, check if a similar proposal has already been approved. ChaSeR allows you to search the database of all observations. Lists of approved programs, which include archive and theory proposals, are also available.

Target Visibility

Once you have selected a target, check to be sure that the object is visible to Chandra during the proposal cycle and that there are no bright sources in the field-of-view that you will need to avoid. You can check target visibility over time using the tool ProVis. The ObsVis software will allow you to inspect sky images with overlaid instrument fields-of-view and facilitates detailed manipulation of Chandra pointing and instrument parameters.

Instrument Selection

Once you know the target is visible to Chandra and has not previously been observed, decide which instrument configuration would work best for your science goals. Detailed information about Chandra instruments is given in the Proposers' Observatory Guide. Additional information can be found in the Instruments and Calibration pages.

Advanced CCD Imaging Spectrometer (ACIS)

The ACIS has two arrays of CCDs, one (ACIS-I) optimized for imaging wide fields (16x16 arc minutes) the other (ACIS-S) optimized as a readout for the HETG transmission grating. One chip of the ACIS-S (S3) can also be used for on-axis (8x8 arc minutes) imaging and offers the best energy resolution of the ACIS system.

For detailed information about ACIS, please refer to Chapter 6 of the POG.

ACIS Operating Modes

Telemetry Options

Selecting ACIS chips

High Resolution Camera (HRC)

The HRC comprises two micro-channel plate imaging detectors, and offers the highest spatial (<0.5 arc second) and temporal (16 msec) resolutions. The HRC-I has the largest field-of-view available on Chandra (31x31 arc minutes). The HRC-S is most commonly used to read out the dispersed spectrum from the LETG. For more information about the HRC, please refer to Chapter 7 of the POG.

High Energy Transmission Grating (HETG)

The HETG is optimized for high-resolution spectroscopy of bright sources over the energy band 0.4-10 keV. It is most commonly used with ACIS-S. The HETG is discussed in detail in Chapter 8 of the POG.

Low Energy Transmission Grating (LETG)

The LETG provides the highest spectral resolving power (E/ΔE > 1000) on Chandra at low energies (0.07 - 0.2 keV). The LETG/HRC-S combination is used extensively for high resolution spectroscopy of bright, soft sources such as stellar coronae, white dwarf atmospheres and cataclysmic variables. The LETG is discussed in detail in Chapter 9 of the POG.

Determining Target Parameters

After choosing an instrument, you should simulate the observation to determine the ideal instrument settings, observing time, constraints (etc.). A variety of tools are available to help with simulating Chandra data. These include such software as PIMMS, Sherpa, WebSpec and the rest of the Proposal Toolkit.

Point Sources

One factor that will affect the exposure time needed to detect a point source is the amount of intervening Hydrogen column density in the direction of the source. COLDEN will give you this information with a limited amount of required input. COLDEN help file

You will also need to determine the predicted Chandra count rate. PIMMS is appropriate to use for calculating count rates for sources with simple spectra. It will also return information about pile-up percentage and the background count rate.

Pileup mitigation is discussed in detail in the POG

ACIS Spectra

Software such as WebSpec and Sherpa can be used to simulate an ACIS spectrum. They can also help you determine whether or not pileup is likely to affect your results.

Grating Spectra

You can simulate HETG spectra with software like Sherpa or ISIS.

When simulating a Chandra grating spectrum, you will likely need to use the Grating RMFs/ARFs for the proposal cycle.

A general method to simulate the spectra would be to first read in the response files, define a model for the spectrum, create a fake Chandra dataset, then assess the output.

Proposal Submission

You will need to prepare Proposal Forms in the RPS proposal submission software that specify the target configuration(s) necessary to meet your science requirements.

A detailed science justification narrative is also required. This document should describe the science objectives of your investigation, explain your data analysis plans and demonstrate technical feasibility. There is a latex template available that you can use to format the document.

A supplemental list of the principal investigator's successful previous proposals is required if they have been approved in previous cycles (including DDT proposals).

You may optionally submit a CV if you are the PI

All requirements (page limits, required information, etc.) for the proposal components are specified in the CfP.