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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"

32510 results found.

  1. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  2. IPN triangulation of GRB 241107A (short/hard)
  3. GRB 241107A: INTEGRAL/IBIS/PICsIT detection of a short burst
  4. GRB 241025C: VZLUSAT-2 detection
  5. GRB 241025A: VZLUSAT-2 detection
  6. GRB 241018A: cubesat Avion detection
  7. GRB 241030B: TESS detection of optical counterpart
  8. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  9. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  11. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  12. EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
  13. LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
  14. EP241107a: AbAO optical upper limit
  15. LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
  16. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  17. LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
  18. LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
  19. EP241109a: confirmation of a stellar flare by BOOTES-7
  20. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  21. EP241107A: MASTER optical observations of xray transient
  22. EP241107a: KAIT optical observations
  23. GRB 241108A: Swift ToO observations
  24. GRB 241030A: TESS observations
  25. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  26. EP241107a: Kinder optical follow-up observations
  27. GRB 241025A: radio detection with the VLA
  28. GRB 241104A: CALET Gamma-Ray Burst Monitor detection
  29. EP241107a: AKO Optical Afterglow Follow-Up Observations
  30. EP241107a: GSP detects optical counterpart
  31. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  32. GRB 241105A: EP-FXT follow-up observations
  33. GRB 241105A: SVOM/GRM observation
  34. EP241107a: OHP/T193 photometric and spectroscopic observations
  35. GRB 241105a: PRIME near-infrared upper limits
  36. EP241107a: FTW Optical and NIR observations of the optical counterpart
  37. GRB 241105A: ePESSTO+ NTT optical afterglow detection
  38. EP241107a: GIT optical observations
  39. EP241107a: Global MASTER-Net observations report
  40. EP241107a: SVOM/C-GFT optical observations
  41. EP241107a: AKO Optical Afterglow Detection
  42. GRB 241025A: LBT optical observations
  43. GRB241105A: Gemini-South Optical Afterglow Detection
  44. GRB 241105A: VLT/FORS2 optical afterglow rapid fading
  45. GRB 241105A: Swift/UVOT Detection
  46. EP241101a: CrAO ZTSH optical observations
  47. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  48. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  49. GRB 241030A: Mondy optical observations
  50. GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  51. Konus-Wind detection of GRB 241105A (short with extended emission)
  52. Konus-Wind detection of GRB 241021A
  53. GRB 241105A: SVOM/VT optical afterglow observations
  54. GRB 241105A: Swift-XRT afterglow detection
  55. GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
  56. GRB 241104A: Swift-XRT observations
  57. GRB 240511A: LCO upper limits
  58. GRB 241104A: Fermi GBM Observation
  59. GRB 241104A: The SVOM/VT candidate in GCN circular 38086 is not an astrophysical source
  60. GRB 241105A: Swift ToO observations
  61. GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
  62. GRB 241104A: Swift ToO observations
  63. GRB 241104A: NOT optical non-detection
  64. GRB 241105A: GOTO tentative optical counterpart candidate
  65. Fermi GRB 241105A: Global MASTER-Net observations report
  66. GRB 241104A: SVOM/VT optical candidate
  67. GRB 241104A/EP241104a: Optical upper limits with Kinder observations
  68. GRB 241104A: COLIBRÍ Upper Limits on the Optical Counterpart
  69. GRB 241104A: SVOM/GRM observation
  70. EP241104a: EP detection of GRB 241104A X-ray emission
  71. GRB 241010A: host galaxy redshift z = 0.977
  72. EP241101a NUTTelA-TAO / BSTI Measurements 2024-11-02
  73. GRB 241104A : Detection and localization by SVOM/ECLAIRs
  74. GRB 240821A: further radio observations with the VLA
  75. Fermi GRB 241104A: Global MASTER-Net observations report
  76. GRB 241030A: GRBAlpha detection
  77. EP241101a: EP-FXT observations update
  78. EP241103a: GIT optical upper limit
  79. EP241021a: OHP/T193 further optical observations
  80. LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
  81. LIGO/Virgo/KAGRA S241102cy: Updated Sky localization
  82. EP241103a: GOTO optical upper limit
  83. LIGO/Virgo/KAGRA S241102br: Updated Sky localization
  84. EP241101a: Possible detection of an optical counterpart with FTW
  85. EP241103a: Swift XRT detection and improved X-ray position
  86. EP241021a: continued SOAR observations
  87. EP241101a: Optical upper limits with Kinder observations
  88. EP241101a: OHP/T193 optical observations
  89. EP241103a: Gemini optical limits
  90. EP241103a: EP observation update
  91. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  92. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  93. EP241103a: GSP optical upper limit
  94. EP241103A: LCO optical observations
  95. EP241103a: Global MASTER-Net observations report
  96. GRB 241030A: Rapid release of TESS data.
  97. EP241101a: Global MASTER-Net observations report
  98. GRB 241029A: GRBAlpha detection
  99. LIGO/Virgo/KAGRA S241101ee: Updated Sky localization
  100. S241102cy: Identification of a GW compact binary merger candidate

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