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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"

5833 results found.

  1. LIGO/Virgo S240919bn: GOTO optical upper limits
  2. GRB 240918B: AstroSat CZTI detection
  3. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  5. EP240919a: EP-FXT follow-up observation update
  6. EP240913A/GRB 240913C: AbAO optical upper limit
  7. EP240919a / GRB 240919A: Mondy optical upper limit
  8. EP240913a/GRB 240913C: 1.6m Mephisto observations
  9. EP240918a: SVOM/VT upper limit
  10. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  11. GRB 240919A / EP240919a: SVOM/GRM observation
  12. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  13. EP EP240919a: Global MASTER-Net observations report
  14. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  15. EP240919a: NOT and Gemini optical observations
  16. EP240919a: GOTO optical upper limits
  17. EP240919a: JinShan optical upper limits
  18. EP240919a is likely a GRB event
  19. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
  20. EP240919a: EP-WXT detection of a fast X-ray transient
  21. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  22. EP240918a: EP observation update
  23. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  24. EP240918a: Swift-XRT observation
  25. Fermi GRB 240918A: Global MASTER-Net observations report
  26. EP EP240918a: Global MASTER-Net observations report
  27. EP240918a: JinShan optical upper limits
  28. EP240918a: YAHPT Optical Upper Limit
  29. EP240918a: GMG Optical Upper Limit
  30. GRB 240916A: GRBAlpha detection
  31. GRB 240914B: GRBAlpha detection
  32. EP240918a: an X-ray transient detected by Einstein Probe
  33. GRB 240916A: NOT optical observation
  34. LIGO/Virgo/KAGRA S240917cb: Identification of a GW compact binary merger candidate
  35. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  36. LIGO/Virgo/KAGRA S240915b: NED Galaxies in the Localization Volume
  37. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  38. GRB 240914B: Fermi GBM Final Localization
  39. The EP-WXT triggers 01709047257 and 01709047278 are not real sources
  40. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  41. EP EP240913a: Global MASTER-Net observations report
  42. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  43. EP240913a: VLT/HAWK-I near-infrared upper limits
  44. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  45. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  46. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  47. GRB 240913C: Joint location by ETJASMIN
  48. GRB 240914B: AstroSat CZTI detection
  49. EP240913A / GRB 240913C: AstroSat CZTI detection
  50. GRB 240914A: SVOM/GRM observation
  51. GRB 240910A: SVOM/VT optical observations
  52. EP240913a: NOT optical upper limits
  53. EP240913a: JinShan optical upper limits
  54. EP240913a: ESO-NTT optical observations
  55. GRB 240914A: ESO-NTT optical observations
  56. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  57. GRB 240914B: BALROG localization (Fermi Trigger 747990592 / GRB 240914298)
  58. GRB 240914A : An intermediate duration GRB located on-board by SVOM/ECLAIRs.
  59. GRB 240905E: further NOT optical observations
  60. EP240913a: A GRB Event
  61. EP240913a: EP-WXT detection of a fast X-ray transient
  62. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  63. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  64. Fermi trigger No 747920561: Global MASTER-Net observations report
  65. GRB 240912A: SVOM/GRM observation
  66. Fermi GRB 240913A: Global MASTER-Net observations report
  67. GRB 240912A: J-band observations with WINTER
  68. Swift GRB 240912A: Global MASTER-Net observations report
  69. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  70. GRB 240912A: NOT optical spectroscopy
  71. GRB 240912A: Redshift from OSIRIS+/GTC
  72. GRB 240910A: Redshift from OSIRIS+/GTC
  73. GRB 240911A : a likely weak GRB detected by SVOM/ECLAIRs
  74. GRB 240910A: GOTO candidate optical counterpart
  75. GRB 240825A: 7DT Optical Upper Limit
  76. GRB 240905E: SVOM/VT optical observations
  77. GRB 240910A: GRBAlpha detection
  78. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  79. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  80. GRB 240910A: SVOM/GRM observation
  81. EP240908a: Mondy and AbAO follow-up observations
  82. EP240908a: Updates on the WXT detection result around the trigger time
  83. Fermi GRB 240910A: Global MASTER-Net observations report
  84. EP EP240908a: Global MASTER-Net observations report
  85. Fermi trigger No 747553301: Global MASTER-Net observations report
  86. EP240908a: TRT optical upper limit
  87. GRB 240905B: GOTO optical upper limits
  88. EP240908a: EP detection of a fast X-ray transient
  89. Fermi GRB 240908A: Global MASTER-Net observations report
  90. LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
  93. GRB 240905E: GIT optical upper limit
  94. GRB 240905E: Gaoyazi/GOT optical upper limits
  95. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  96. GRB 240905E: J-band observations with WINTER
  97. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  98. Fermi GRB 240905D: Global MASTER-Net observations report
  99. Fermi GRB 240905A: Global MASTER-Net observations report
  100. GRB 240905E: NOT optical upper limits

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