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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"

4058 results found.

  1. LIGO/Virgo/KAGRA S230608as: Identification of a GW compact binary merger candidate
  2. LIGO/Virgo/KAGRA S230602ap: Zwicky Transient Facility observations
  3. LIGO/Virgo S230606z: Global MASTER-Net observations report
  4. LIGO/Virgo S230606d: Global MASTER-Net observations report
  5. LIGO/Virgo/KAGRA S230606d: Identification of a GW compact binary merger candidate
  6. LIGO/Virgo/KAGRA S230605o: Updated Sky localization
  7. IceCube-230603A: Upper limits from a search for additional neutrino events in IceCube
  8. LIGO/Virgo/KAGRA S230601bf: Updated Sky localization
  9. LIGO/Virgo/KAGRA S230605o: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo S230605o: Global MASTER-Net observations report
  11. LIGO/Virgo S230604z: Global MASTER-Net observations report
  12. LIGO/Virgo S230603aa: Global MASTER-Net observations report
  13. LIGO/Virgo S230602ap: Global MASTER-Net observations report
  14. LIGO/Virgo/KAGRA S230518h: Upper limits from a two-week IceCube neutrino search
  15. LIGO/Virgo S230601bf: Global MASTER-Net observations report
  16. LIGO/Virgo/KAGRA S230601bf: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo S230531f: Global MASTER-Net observations report
  18. LIGO/Virgo/KAGRA S230529ay: Zwicky Transient Facility observations
  19. LIGO/Virgo/KAGRA S230528a: Zwicky Transient Facility observations
  20. LIGO/Virgo/KAGRA S230527ch: Zwicky Transient Facility observations
  21. LIGO/Virgo/KAGRA S230529ay: Upper limits from CALET observations.
  22. LIGO/Virgo/KAGRA S230529ay: AstroSat CZTI non-detection and upper limits
  23. LIGO/Virgo S230529ay: Global MASTER-Net observations report
  24. LIGO/Virgo/KAGRA S230529ay: upper limits from AGILE/MCAL
  25. LIGO/Virgo/KAGRA S230529ay: Coverage and upper limits from MAXI/GSC observations
  26. LIGO/Virgo/KAGRA S230529ay: Upper limits from Fermi-GBM Observations
  27. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  28. LIGO/Virgo/KAGRA S230529ay: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  29. LIGO/Virgo/KAGRA S230529ay: Identification of a GW compact binary merger candidate
  30. LIGO/Virgo S230529p: Global MASTER-Net observations report
  31. LIGO/Virgo S230525a: Global MASTER-Net observations report
  32. LIGO/Virgo/KAGRA S230518h: Updated Sky localization
  33. LIGO/Virgo/KAGRA S230520ae: Updated Sky localization
  34. LIGO/Virgo/KAGRA S230518h: Upper limits from Glowbug gamma-ray observations
  35. LIGO/Virgo/KAGRA S230518h: TESS observations of the localization region
  36. LIGO/Virgo/KAGRA S230518h: No transient candidates in CALET observations
  37. LIGO/Virgo/KAGRA S230524x: Retraction of GW compact binary merger candidate
  38. LIGO/Virgo S230524b: Global MASTER-Net observations report
  39. LIGO/Virgo/KAGRA S230521k: MASTER new OT discovery
  40. LIGO/Virgo/KAGRA S230521k: Additional candidates from Zwicky Transient Facility
  41. LIGO/Virgo S230522n: Global MASTER-Net observations report
  42. LIGO/Virgo S230522a: Global MASTER-Net observations report
  43. LIGO/Virgo/KAGRA S230522n: Upper limits from IceCube neutrino search
  44. LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for MeerLICHT candidates: AT2023ixg and AT2023iyb
  45. LIGO/Virgo/KAGRA S230522a: 2 counterpart neutrino candidates from IceCube neutrino searches
  46. LIGO/Virgo S230521k: Global MASTER-Net observations report
  47. LIGO/Virgo/KAGRA S230521k: Zwicky Transient Facility observations
  48. LIGO/Virgo S230520ae: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S230520ae: Identification of a GW compact binary merger candidate: End-to-End Test
  50. LIGO/Virgo/KAGRA S230520ae: Upper limits from IceCube neutrino search
  51. LIGO/Virgo/KAGRA S230518h: ATCA follow-up of candidate counterparts
  52. LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
  53. LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for Swope candidates: SSS23a, SSS23b and SSS23c
  54. LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
  55. LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
  56. LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
  57. LIGO/Virgo S230518h: AGILE/MCAL observations
  58. LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
  59. LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
  60. LIGO/Virgo/Kagra S230518h: NED Galaxies in the Localization Volume
  61. LIGO/Virgo/KAGRA S230518h: AstroSat CZTI non-detection and upper limits
  62. LIGO/Virgo/KAGRA S230518h: Upper limits from Fermi-GBM Observations
  63. LIGO/Virgo S230518h: Global MASTER-Net observations report
  64. LIGO/Virgo/KAGRA S230518h: Updated Sky localization and EM Bright Classification
  65. LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  66. LIGO/Virgo S230518h: Upper limits from IceCube neutrino search
  67. LIGO/Virgo/KAGRA S230518h: Identification of a GW compact binary merger candidate
  68. IceCube-230511A: Upper limits from a search for additional neutrino events in IceCube
  69. IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
  70. GRB 230423A: Swift/UVOT Upper Limits
  71. New GCN Circulars Portal for Rapid Communications on Astronomical Transients is Online
  72. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  73. GRB 221215A: Swift/BAT-GUANO arcminute localization
  74. GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
  75. LIGO-Virgo-KAGRA and GEO600 statement on GRB 221009A
  76. IPN triangulation of GRB 220927A (long)
  77. GRB 220909A: Swift/BAT-GUANO candidate arcminute localization
  78. IPN triangulation of GRB 220903A (long)
  79. GRB 220831A: Swift/BAT-GUANO localization of a short burst
  80. Introducing new GCN Kafka broker and web site for transient alerts, https://gcn.nasa.gov
  81. GRB 220710A: Swift/BAT-GUANO arcminute localization
  82. IPN triangulation of GRB 220711C (short)
  83. GRB 220708B: Swift/BAT-GUANO arcminute localization
  84. GRB 220606B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  85. IPN triangulation of GRB 220601A (long)
  86. Fermi-GBM will trial new SAA regions from Tuesday June 7th
  87. IPN triangulation of GRB 220524B
  88. IPN triangulation of GRB 220524A
  89. IPN triangulation of GRB 220521B
  90. IPN triangulation of GRB 220519A
  91. GRB 220514A: MITSuME Akeno optical observation
  92. GRB 220511A: Swift/BAT-GUANO arcminute localization
  93. IPN triangulation of GRB 220411A
  94. IPN triangulation of short/soft GRB 220406A
  95. GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
  96. IPN triangulation of GRB 220308A (long / very bright)
  97. IPN triangulation of GRB 220222A
  98. GCN Circ.draft on GRB 220222A
  99. ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
  100. IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)

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Download all Circulars as a .tar.gz archive (updated once a day):
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