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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"

20857 results found.

  1. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  2. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  3. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo S240919bn: GOTO optical upper limits
  5. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  6. GRB 240918B: AstroSat CZTI detection
  7. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  9. EP240913A/GRB 240913C: AbAO optical upper limit
  10. EP240919a / GRB 240919A: Mondy optical upper limit
  11. EP240913a/GRB 240913C: 1.6m Mephisto observations
  12. EP240918a: SVOM/VT upper limit
  13. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  14. EP240919a / GRB 240919A: REM optical and NIR upper limits
  15. EP240918b and EP240918c: Optical upper limits with Kinder observations
  16. GRB 240414A: further radio observations with the VLA
  17. EP240919a: Optical upper limit with Kinder observations
  18. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  19. GRB 240910A: radio detection with the VLA
  20. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  21. EP240919a: NOT and Gemini optical observations
  22. EP240919a: GOTO optical upper limits
  23. EP240919a: JinShan optical upper limits
  24. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S240917cb: Updated Sky localization and EM Bright Classification
  26. LIGO/Virgo/KAGRA S240916ar: Updated Sky localization and EM Bright Classification
  27. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  28. GRB 240910A: further Swift observations and confirmation of afterglow
  29. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  30. EP240918a: JinShan optical upper limits
  31. EP240918a: Optical upper limits with Kinder observations
  32. EP240918a: GMG Optical Upper Limit
  33. EP240918a: an X-ray transient detected by Einstein Probe
  34. GRB 240916A: NOT optical observation
  35. IPN triangulation of GRB 240913C / EP 240913a
  36. LIGO/Virgo/KAGRA S240917cb: Identification of a GW compact binary merger candidate
  37. GRB 240821A: radio observation with the VLA
  38. GRB 240916A: Swift-XRT afterglow detection
  39. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  40. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  41. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  42. EP240913a: VLT/HAWK-I near-infrared upper limits
  43. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S240915b: Updated Sky localization and EM Bright Classification
  45. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  46. GRB 240914A: Swift-XRT observations
  47. GRB 240910A: SVOM/VT optical observations
  48. EP240913a: NOT optical upper limits
  49. EP240913a: JinShan optical upper limits
  50. EP240913a: ESO-NTT optical observations
  51. GRB 240914A: ESO-NTT optical observations
  52. GRB 240905E: further NOT optical observations
  53. EP240913a: EP-WXT detection of a fast X-ray transient
  54. GRB 240911A: LCO optical observations
  55. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  56. GRB 240912A: Swift/UVOT Detection
  57. GRB 240911A: Swift-XRT observations
  58. GRB 240912A: J-band observations with WINTER
  59. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  60. GRB 240912A: Enhanced Swift-XRT position
  61. GRB 240912A: Redshift from OSIRIS+/GTC
  62. Fast X-ray Transient EP240801a: GMRT radio observations
  63. GRB 240910A: Redshift from OSIRIS+/GTC
  64. GRB 240912A: Swift detection of a burst with an optical counterpart
  65. GRB 240910A: JinShan optical observations
  66. IPN triangulation of GRB 240905B (short)
  67. GRB 240825A: 7DT Optical Upper Limit
  68. GRB 240905E: SVOM/VT optical observations
  69. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  70. LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
  71. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  72. GRB 240910A: SVOM/GRM observation
  73. EP240908a: Mondy and AbAO follow-up observations
  74. EP240908a: TRT optical upper limit
  75. EP240908a: EP detection of a fast X-ray transient
  76. LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
  77. LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
  79. GRB 240905E: GIT optical upper limit
  80. GRB 240905B: Swift-XRT observations
  81. GRB 240905E: Gaoyazi/GOT optical upper limits
  82. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  83. GRB 240905B: Fermi-LAT detection
  84. GRB 240905E: J-band observations with WINTER
  85. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  86. GRB 240905E: AKO Optical Upper Limit
  87. GRB 240905E: SVOM/C-GFT optical upper limit
  88. GRB 240905E: OHP/MISTRAL T193 optical upper limit
  89. GRB 240905E: NOT optical upper limits
  90. GRB 240905E: REM optical/NIR upper limits
  91. GRB 240902B: AstroSat CZTI detection of a long burst
  92. GRB 240905E: LCOGT Optical Upper Limit
  93. GRB 240905E: Swift/UVOT Upper Limits
  94. GRB 240905E: SAO RAS optical upper limit
  95. GRB 240905E: Nanshan/HMT optical upper limit
  96. GRB 240905E: Swift detection of a burst
  97. GRB 240819A: Optical upper limits from TESS
  98. GRB 240904A: Swift detection of a burst
  99. LIGO/Virgo/KAGRA S240902bq: Identification of a GW compact binary merger candidate
  100. GRB 240825A: MeerLICHT afterglow detection

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