Observations of Messier 51 from many telescope archives

This case study searches for X-ray observations of the Messier 51 galaxy, taken by a variety of X-ray telescopes. We chose this galaxy because it is active (and thus likely X-ray bright), and nearby - this makes it a priority target for many X-ray observatories. This process could equally be applied to any named object (or object at a specific set of coordinates).

Import Statements

[1]:

from warnings import warn

from daxa.mission import XMMPointed, Chandra, ASCA, Suzaku, ROSATPointed, ROSATAllSky
from daxa.archive import Archive
from daxa.exceptions import NoObsAfterFilterError

Defining missions

We create instances of the XMM, Chandra, ASCA, Suzaku, ROSAT Pointed, and ROSAT All-Sky missions in order to search their archives - other missions are supported by DAXA (and can be found in the missions tutorial), but these are a subset likely to have observations of M51:

[2]:

xm = XMMPointed()
ch = Chandra()
asc = ASCA()
su = Suzaku()
rp = ROSATPointed()
ra = ROSATAllSky()

/Users/dt237/code/DAXA/daxa/mission/xmm.py:83: UserWarning: 140 of the 17697 observations located for this mission have been removed due to NaN RA or Dec values
  self._fetch_obs_info()
/Users/dt237/code/DAXA/daxa/mission/asca.py:91: UserWarning: 5 of the 3079 observations located for ASCA have been removed due to all instrument exposures being zero.
  self._fetch_obs_info()
/Users/dt237/code/DAXA/daxa/mission/suzaku.py:96: UserWarning: 14 of the 3055 observations located for Suzaku have been removed due to all instrument exposures being zero.
  self._fetch_obs_info()

Searching for observations

In this instance we use the filter_on_name method to search for observations of M51 - this will use the Sesame name resolver to look-up the coordinates for the object. Alternatively, we could use the filter_on_positions method and supply the coordinate ourselves:

[3]:

xm.filter_on_name("M51")
ch.filter_on_name("M51")
asc.filter_on_name("M51")
rp.filter_on_name("M51")
ra.filter_on_name("M51")

/Users/dt237/code/DAXA/daxa/mission/base.py:1075: UserWarning: Chandra FoV are difficult to define, as they can be strongly dependant on observation mode; as such take these as very approximate.
  fov = self.fov
/Users/dt237/code/DAXA/daxa/mission/base.py:97: UserWarning: There are multiple chosen instruments SIS0, SIS1, GIS2, GIS3 for asca with different FoVs, but they observe simultaneously. As such the search distance has been set to the largest FoV of the chosen instruments.
  any_ret = change_func(*args, **kwargs)

We have deliberately separated the Suzaku search, as we are aware that it will not find any matching data - as such we’ll use this to highlight that the standard Python exception-catching statements can be used to stop a failure to find data derailing your script (for instance you might wish to iterate through a list of missions and have a try-except statement like this:

[4]:

try:
    su.filter_on_name("M51")
except NoObsAfterFilterError as err:
    warn(err.message, stacklevel=2)

/opt/anaconda3/envs/daxa_dev/lib/python3.9/site-packages/IPython/core/interactiveshell.py:3433: UserWarning: The positional search has returned no Suzaku observations.
  exec(code_obj, self.user_global_ns, self.user_ns)

Example of observations identified from filtering

We can use the filtered_obs_info property to retrieve the information table describing the accepted observations:

[5]:

rp.filtered_obs_info

[5]:

	ra	dec	ObsID	science_usable	start	end	duration	instrument	with_filter	target_category	target_name	proc_rev	fits_type
368	202.47	47.2	RH600601N00	True	1994-06-18 13:11:33.000000	1994-06-24 08:04:24.000001	0 days 10:05:23	HRI	N	NGS	M 51	2	RDF 3_4
917	202.47	47.2	RP600158N00	True	1991-11-28 16:07:59.999998	1991-12-13 17:50:20.999999	0 days 06:39:16	PSPCB	N	NGS	N5194/N5195	2	RDF 3_4
2904	202.47	47.2	RH600062A03	True	1994-05-22 05:24:01.000002	1994-05-23 07:16:07.000000	0 days 02:36:32	HRI	N	NGS	M51	2	RDF 3_4
3096	202.47	47.2	RH600062A01	True	1992-05-22 23:44:46.000000	1992-06-05 21:50:42.999999	0 days 02:27:11	HRI	N	NGS	M51	2	RFITS V3.
3174	202.47	47.2	RH600062A00	True	1991-12-07 09:46:57.000003	1992-01-10 05:10:12.999996	0 days 02:22:21	HRI	N	NGS	M51	2	RFITS V3.
3303	202.47	47.2	RH601115N00	True	1997-12-26 23:37:19.000001	1997-12-30 07:46:24.000001	0 days 02:15:04	HRI	N	NGS		2	RDF 4_2

Defining an Archive

The filtered missions can then be used to define an archive containing the selected data:

[6]:

arch = Archive('M51', [xm, ch, asc, rp, ra])
arch.info()

Downloading XMM-Newton Pointed data: 100%|████████████████████████████████████| 16/16 [07:37<00:00, 28.60s/it]
Downloading Chandra data: 100%|███████████████████████████████████████████████| 28/28 [02:57<00:00,  6.32s/it]
Downloading ASCA data: 100%|████████████████████████████████████████████████████| 2/2 [01:00<00:00, 30.23s/it]
Downloading ROSAT Pointed data: 100%|███████████████████████████████████████████| 6/6 [00:11<00:00,  1.93s/it]
Downloading RASS data: 100%|████████████████████████████████████████████████████| 2/2 [00:09<00:00,  4.55s/it]


-----------------------------------------------------
Number of missions - 5
Total number of observations - 54
Beginning of earliest observation - 1990-07-11 00:00:00
End of latest observation - 2022-01-08 17:51:21

-- XMM-Newton Pointed --
   Internal DAXA name - xmm_pointed
   Chosen instruments - M1, M2, PN
   Number of observations - 16
   Fully Processed - False

-- Chandra --
   Internal DAXA name - chandra
   Chosen instruments - ACIS-I, ACIS-S, HRC-I, HRC-S
   Number of observations - 28
   Fully Processed - False

-- ASCA --
   Internal DAXA name - asca
   Chosen instruments - SIS0, SIS1, GIS2, GIS3
   Number of observations - 2
   Fully Processed - False

-- ROSAT Pointed --
   Internal DAXA name - rosat_pointed
   Chosen instruments - PSPCB, PSPCC, HRI
   Number of observations - 6
   Fully Processed - False

-- RASS --
   Internal DAXA name - rosat_all_sky
   Chosen instruments - PSPC
   Number of observations - 2
   Fully Processed - False
-----------------------------------------------------