Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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"

7413 results found.

  1. GRB 250103A: SVOM detection of a long burst
  2. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  3. IceCube-250102A - IceCube observation of a high-energy neutrino candidate track-like event
  4. IceCube-250101A - IceCube observation of a high-energy neutrino candidate track-like event
  5. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  6. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  7. GRB 250101A: Swift detection of a burst with an optical counterpart
  8. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  9. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  11. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  12. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  13. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  14. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  15. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  16. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  17. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  18. GRB 241229A: SAO RAS optical observations
  19. GRB 241229B: SVOM/VT optical candidate
  20. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  21. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  22. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  23. GRB 241229A: Swift ToO observations
  24. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  25. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  26. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  27. GRB 241228B: GOTO24jmz optical follow-up observations
  28. GRB 241228B: Swift ToO observations
  29. GRB 241228B: TRT optical counterpart confirmation
  30. GRB 241228B: GOTO possible optical counterpart candidate
  31. GRB 241228A: Swift detection of a burst
  32. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  33. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  34. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  35. IceCube-241224A - IceCube observation of a high-energy neutrino candidate track-like event
  36. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  37. GRB 241223A: Swift ToO observations
  38. EP241217a: 1.6m Mephisto multi-band optical observations
  39. EP241217a: optical upper limit with the Liverpool Telescope
  40. GRB 241218A: Swift detection of a burst
  41. GRB 241217A: LCO optical upper limit
  42. GRB 241217A: GRANDMA/TAROT optical upperlimits
  43. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  44. EP241217a: Kinder optical follow-up observations
  45. GRB 241215A: Mondy AZT-33IK optical observations
  46. The EP-WXT trigger 01709128948 is likely a flaring star
  47. GRB 241215A: Montarrenti Observatory optical upper limit
  48. GRB 241213A: SVOM/VT optical candidate
  49. GRB 241213B: Tiled Swift observations
  50. GRB 241212A: Swift ToO observations
  51. LIGO/Virgo/KAGRA S241210fu: Updated Sky localization
  52. GRB 241213A: Swift detection of a burst
  53. GRB 241209B: GRANDMA/TRT upper limit
  54. GRB 241207A: TSHAO Zeiss-1000 optical observations
  55. GRB 241209A: Redshift of the likely host galaxy z = 0.784 from OSIRIS+/GTC
  56. LIGO/Virgo/KAGRA S241210cw: Updated Sky localization
  57. LIGO/Virgo/KAGRA S241210d: Updated Sky localization and EM Bright Classification
  58. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
  61. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  62. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  63. GRB 241209A: GRANDMA/TAROT upper limit
  64. GRB 241209B: Swift ToO observations
  65. GRB 241209A: VLT/X-shooter spectroscopy
  66. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  67. GRB 241209A: Swift detection of a short burst
  68. GRB 241207C: Tiled Swift observations
  69. EP241201a: 1.6m Mephisto Optical Upper Limits
  70. EP241202b: KAIT optical upper limit
  71. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  72. EP241202b: Kinder optical counterpart candidate
  73. EP241201a: NOT optical observations
  74. EP241201a: Kinder optical counterpart candidate
  75. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  76. LIGO/Virgo/KAGRA S241201ac: Updated Sky localization
  77. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S241130be: Updated Sky localization
  79. LIGO/Virgo/KAGRA S241130n: Updated Sky localization
  80. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  81. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  82. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  83. LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
  84. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  86. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  87. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  88. EP241126a: WFST Observations
  89. GRB 241127A: Swift detection of a burst with an optical counterpart
  90. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  91. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  92. IceCube-241127A: IceCube observation of a high-energy neutrino candidate track-like event
  93. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  94. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  95. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  97. LIGO/Virgo/KAGRA S241126dm: Retraction of GW compact binary merger candidate
  98. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  99. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  100. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov