Skip to main content
New! Browse Circulars by Event, Advanced Search, Sample Codes, Schema Release. See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

20819 results found.

  1. MISTRAL@OHP photometric and spectroscopic observations of GRB 241029A
  2. GRB 241026A: Swift/UVOT Upper Limits
  3. GRB 241029A: AKO Optical Afterglow Detection
  4. GRB 241029A: GOTO optical afterglow detection
  5. EP241021a: continued SOAR observations confirm optical rebrightening
  6. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  7. GRB 241029A: Mephisto observations
  8. EP 241026b: LBT possible optical counterpart (brightening source)
  9. GRB 241029A: TRT optical afterglow candidate detection
  10. GRB 241026A: TNOT optical counterpart detection
  11. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  12. GRB 241025A: further SAO RAS optical observations
  13. GRB 241026A: BTA and Zeiss-1000 optical observations
  14. GRB 241026A: SVOM/GRM observation
  15. EP241026B: GROWTH-India Telescope optical upper limit
  16. GRB 241025A: Swift/UVOT Detection
  17. GRB 241026A: GROWTH-India Telescope optical observations
  18. GRB 241026A: J-band observations with WINTER
  19. GRB 241025A: SAO RAS optical observations
  20. GRB 241026A: Las Cumbres optical detection
  21. GRB 241025A: Mondy optical observations
  22. EP241021a: SOAR observations of the optical counterpart
  23. EP241021a: further SAO RAS optical observations
  24. EP 241026b: LBT optical observations
  25. EP241021a: e-MERLIN radio observation
  26. GRB 241026A: Enhanced Swift-XRT position
  27. EP241026b: EP detection of a fast X-ray transient
  28. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  29. GRB 241026A: SAO RAS observations of possible optical afterglow
  30. GRB 241026A: Swift detection of a burst
  31. GRB241025A: 1.3m DFOT optical afterglow detection
  32. EP241021a: optical follow-up observations with Xinglong Observatory
  33. GRB 241025A: GROWTH-India Telescope optical observations
  34. GRB 241025A: COLIBRÍ Detection of the Afterglow
  35. GRB 241025A: Fermi GBM Observation
  36. IPN triangulation of GRB 241022A (short/hard)
  37. EP 241021a: Swift-XRT observations
  38. EP241021a: optical follow-up observations with the Liverpool Telescope
  39. GRB 241025A : SVOM/VT optical afterglow observations
  40. EP241021a: Liverpool Telescope optical follow-up observations
  41. GRB 241025A: Enhanced Swift-XRT position
  42. GRB 241025A: DDOTI Afterglow detection
  43. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  44. GRB 241025A: TRT optical afterglow observation
  45. GRB 241025A: Swift detection of a burst with an optical counterpart
  46. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  47. GRB 241001A: ATCA radio observations
  48. GRB 241010A: VIRT Optical Upper Limit
  49. EP241021a: SAO RAS optical observations
  50. EP241021a: KAIT optical observations
  51. IPN triangulation of GRB 241021A (long)
  52. EP241021a: 1.3m DFOT Optical observations
  53. EP241021a: Optical upper limits with Kinder observations
  54. EP241021a: TRT optical observations
  55. GRB 241018A: SVOM/C-GFT optical observations
  56. EP241021a: NOT likely optical counterpart
  57. GRB241017A: 1.3m DFOT optical upper limit
  58. GRB 241018A: 1.3m DFOT Optical upper limit
  59. EP241021a: GOTO optical upper limits
  60. EP241021a: EP detection of a fast X-ray transient
  61. Konus-Wind detection of GRB 241018A
  62. GRB 241018A/sb24101802: Mephisto optical upper limit
  63. GRB 241017A/sb24101702: Mephisto optical upper limit
  64. GRB 241018A: Mondy optical upper limit
  65. GRB 241018A: GROWTH-India telescope optical upper limit
  66. GRB241018A: XingLong Optical Upper Limit
  67. GRB 241018A: Swift-XRT observations
  68. GRB 241018A: REM optical/NIR upper limits
  69. GRB 241018A: NOT optical observations
  70. GRB 241017A: SVOM/VT follow-up and optical upper limit
  71. GRB 241018A: SVOM/VT follow-up and optical candidate
  72. GRB 241018A: LCO/0.4m optical upper limits
  73. GRB 241006A: VIRT Optical Upper Limit
  74. GRB 240727A: VIRT Optical Upper Limit
  75. GRB 241018A: X-ray afterglow candidate observed by MXT
  76. GRB 241017A: Swift-XRT observations
  77. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  78. GRB 241017A: GROWTH-India Telescope optical upper limit
  79. GRB241017A: TOO Observations by SVOM/MXT
  80. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  81. GRB 241017A: J-band upper limit from WINTER
  82. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  83. GRB 240916A: radio detection with the VLA
  84. GRB241013A: REM observations
  85. GRB 241009A: LCO optical upper limits
  86. LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
  87. LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
  88. GRB 241009A: GRANDMA optical upper limits
  89. GRB 241009A: Swift-XRT afterglow detection
  90. GRB 241010A: JinShan optical observations and potential host galaxy
  91. GRB 241006A: ATCA Radio Upper Limits
  92. LIGO/Virgo/KAGRA S241007bw: Updated Sky localization
  93. GRB 241010A: J-band observations with WINTER
  94. GRB 241010A: Enhanced Swift-XRT position
  95. GRB 241010A: LCO optical observations
  96. GRB 241010A: Swift detection of a burst with an optical counterpart
  97. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  98. GRB 241002B: Swift-XRT afterglow detection
  99. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  100. GRB 241002A: NOT optical upper limits

Advanced

Download all Circulars as a .tar.gz archive:
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov