# Time axis phase

**URL:** https://forum.generic-mapping-tools.org/t/time-axis-phase/5980
**Category:** Q&A
**Created:** [June 3, 2025, 2:40pm UTC](https://forum.generic-mapping-tools.org/t/time-axis-phase/5980 "2025-06-03T14:40:04Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![cpaitor](https://avatars.discourse-cdn.com/v4/letter/c/35a633/32.png) [@cpaitor](https://forum.generic-mapping-tools.org/u/cpaitor)
#### Post date: [June 3, 2025, 2:40pm UTC](https://forum.generic-mapping-tools.org/t/time-axis-phase/5980/1 "2025-06-03T14:40:04Z")

</div>

Hi

(tested on GMT 5.4.3 and 6.4.0)

In plotting a time axis it seems that the tick/grid/label location always aligns with the first day of the month (for unit D of the stride). E.g. with -Bxa7D for the interval 2025-04-19 to 2025-05-03 I get tick/grid/labels at 2025-04-22, 2025-04-29, 2025-05-01 but would like to get them at 2025-04-19, 2025-05-26, 2025-05-03. Is there a way to achieve this? I tried to shift the tick/grid/labels by specifying a phase on the -Bx option but no avail, but it is a bit unclear to me how the phase should be specified for a time axis.

---

<div class="post-metadata">

### Author: ![mkononets](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/mkononets/32/4029_2.png) [@mkononets](https://forum.generic-mapping-tools.org/u/mkononets)
#### Post date: [June 3, 2025, 9:13pm UTC](https://forum.generic-mapping-tools.org/t/time-axis-phase/5980/2 "2025-06-03T21:13:57Z")

</div>

It doesn’t look like specifying phase works for time axis and there seems to be no examples in [the docs](https://docs.generic-mapping-tools.org/latest/reference/options.html#cartesian-time-axes). [Custom annotations](https://docs.generic-mapping-tools.org/latest/reference/options.html#custom-axes) via `-Bxc...` work.

```auto
cat << EOF > xannot.txt                                                  
2025-04-19T a 2025-04-19
2025-04-26T a 2025-04-26
2025-05-03T a 2025-05-03
EOF
gmt basemap -JX10c/1c -R2025-04-19T/2025-05-03T/0/1 -Bxcxannot.txt -BwSne -png time_axis_phase.png

```

 ![time_axis_phase](https://canada1.discourse-cdn.com/flex047/uploads/gmt/original/2X/8/808740e945ef41a7a7164d458536b45e0548bcba.png)

---

<div class="post-metadata">

### Author: ![cpaitor](https://avatars.discourse-cdn.com/v4/letter/c/35a633/32.png) [@cpaitor](https://forum.generic-mapping-tools.org/u/cpaitor)
#### Post date: [June 4, 2025, 6:17am UTC](https://forum.generic-mapping-tools.org/t/time-axis-phase/5980/3 "2025-06-04T06:17:11Z")

</div>

Ok, that was my suspicion as well but I was hoping to be wrong. Thanks for your input.